The Ancient History of Assam begins with the Ancient kingdom of Kamrupa.  Some  of  the  major dynasties of Kamrupa are:

1. Varman Dynasty
2. Salasthambha Dynasty
3. Pala Dynasty

Kamarupa also called Pragjyotisha or Pragjyotisha-Kamarupa), an early state during the Classical period on the Indian subcontinent was (along with Davaka) the first historical  kingdom  of Assam. Though Kamarupa existed from 350 CE to 1140 CE, Davaka was absorbed by Kamarupa in the  5th century CE.
Ruled by three dynasties from their capitals in present-day Guwahati, North Guwahati and Tezpur, Kamarupa at its height covered the entire Brahmaputra Valley, North Bengal, Bhutan and northern part of Bangladesh, and at times portions of what is now West Bengal and Bihar.
Though the historical kingdom disappeared by the 12th century to be replaced by smaller political entities, the notion  of Kamarupa persisted and ancient and medieval chroniclers continued to call this region by this name. In the 16th century the Ahom kingdom came into prominence and assumed for itself the political and territorial legacy of the Kamarupa kingdom. The earliest mention of a kingdom comes from the 4th-century Allahabad inscription of Samudragupta that calls the kings of Kamarupa and Davaka frontier rulers (pratyanta nripati).
The   Chinese   traveler Xuanzang visited   the   kingdom    in    the    7th    century,    then    ruled by Bhaskaravarman. The corpus of Kamarupa inscriptions left by the rulers of Kamarupa, including Bhaskaravarman, at various places in Assam and present-day Bangladesh are important sources of information. Nevertheless, local grants completely eschew the name Kamarupa; instead they use the name Pragjyotisha, with the kings called Pragjyotishadhipati. According to the 10th century Kalika Purana and the 7th century Xuanzang, the western boundary was the historical Karatoya River. The eastern border was the temple of the goddess Tamreshvari (Pūrvāte Kāmarūpasya devī Dikkaravasini, given in Kalika Purana) near present-day Sadiya.The southern boundary was near the border between the Dhaka and Mymensingh districts in Bangladesh. Thus it spanned the entire Brahmaputra  valley  and Northeast  India and  at  various  times   included   parts   of   present day Bhutan, Bangladesh and Nepal.
The kingdom appears to have broken up entirely by the 13th century into smaller kingdoms and from   among    them    rose    the Kamata    kingdom in    the    west    and    the Ahom, Dimasa and the Chutiya kingdoms as the main successors, with the Baro-Bhuyans ruling intervening areas.
Davaka  was   a    kingdom    of  ancient    Indian    subcontinent,    located    in    current    central    region of Assam state. The  references  to   it   comes   from   the   4th   century   Allahabad   pillar   inscription of Samudragupta, where it is mentioned as one of five frontier kingdoms of the Gupta Empire; the Shung-Shu History of the Liu Song dynasty, where the kingdom  is named Kapili (now the name  of a river); the Gachtal stone pillar inscription written in Kamrupi Prakrit. N K Bhattasali has identified it with Dabaka in modern Nagaon district, with the  kingdom  associated  with  the Kopili-Kolong river valley.
In  4th-century  Davaka  was  mentioned  as  frontier  kingdom  with Kamarupa in  the Samudragupta’s Prayaga stone inscription, which was later absorbed by 6th or 7th century by western kingdom of Kamarupa. Though later historians like B N Puri (1968) and P C Choudhury (1959) claim that it was absorbed much earlier in the first half of the 5th century during the reign of Kalyana Varman (422-446).Its capital was located near Kapili river. In the year 428 A.D, an embassy was sent to China by Davaka king, whose name according to Chinese sources is Yuegnai or Yu Chai.

Rulers of the Varman Dynasty
Varman Dynasty (c 355-650)
The Varman dynasty was the first historical dynasty of the Kamarupa kingdom. It was established by Pushyavarman, a contemporary of Samudragupta The kingdom which he established with much effort, grew in the periphery of the Gupta Empire, adopted the north Indian political model, and its kings took on names and titles of the Gupta kings and queens.The earlier  Varmans  were subordinates of the Gupta Empire, but as the power of the Guptas waned, Mahendravarman (470- 494) performed two horse sacrifices and status of Kamarupa as Independent state remained unimpaired

                             
According to Allahabad Prasasti  of  Samudragupta,  the  ruler  of  Kamarupa  was  mentioned  as  a frontier ruler (Pratyanta-nrpatis) of the great Gupta emperor. As per Apsad Inscription of Adityasen, Susthivarman was defeated by Mahasengupta on the bank of Lauhitya.
The  capital  was  Pragjyotishpura  and located  at   the   south-eastern   slope   of   the   Narakasur   hill near Dispur.    The     dynastic line    from     Pushyavarman     first     appear     in     the     7th     century, in Dubi and Nidhanpur copperplate       inscriptions       issued        by        Bhaskaravarman        and        in the Harshacharita, though  the  descriptions  are  panegyric,  repetitive  and  devoid  of   dates.Though some modern scholars have opined that the Varman dynasty is probably of Indo-Aryan descent, it is now believed that the Varmans were originally non-Indo-Aryans.
Suniti Kumar Chatterjee calls Bhaskaravarman a Hinduised Mlechcha king of Indo-Mongoloid origin. Hugh B. Urban (2011) too infers that the Varmans descended from non-Aryan tribes.

Important Rulers:
Pushya Varman (c. 350-380 AD)

• Founder of Varman Dynasty
• Contemporary of great Gupta Ruler Samudra Gupta
• Took the title-MaharajadhirajalI
• Ensured steps to establish Kamrupa as a frontier state

Samudra Varman (c. 380-405 AD)

• Son of Pushya Varman
• Contemporary of great Gupta Ruler Chandra Gupta II (Vikramaditya)

Mahendra Varman (c. 450-485 AD)

• First Varman Dynasty king to conduct Aswamedh ritual.
• The first king of Kamrupa who waged a successful war against Gupta army.
• He possibly liberated Varman Dynasty from Gupta dominance.

Mahabhuti Varman (c. 510-555 AD)

•  During his reign a big portion of north bengal and bihar was included within the kingdom of kamrupa
• Came to be known as Parama Bhagavata (Inclination towards vasihnavism)

After Mahabhuti Varman , certain later varman rulers showed weakness  and  consequently  were defeated by later Guptas As a result, the Kingdom of Kamrupa contracted in the west and the river Karotoya became the boundary

Bhaskar Varman

• Last and greatest king of the Varman dynasty and a contemporary of Harshavardhan (606- 648 AD)
• Harshavardhan honoured Bhaskar Varman at a conference held at Kanauj
• During his reign, Kamrupa became a dominant power in all India politics.
• He jointly with Harshavardhana of Kanauj defeated ruler of Bengal called Sasanka and forced him to flee to Orissa

Chinese traveller Hiuen Tsang lived in the court of Bhaskar varman for some time

• Assamese Calendar (Bhāskarābda) is counted from the date of the ascension of Kumar Bhaskar Barman to the throne of Kamrup
• The  achievements  of  Bhaskar  Varman  are  mentioned  in  Bana  Bhatta‘s  ‗Harsha-Charita‘, Hiuen Tsang‘s ‗Si-Yu-Ki‘  and various inscriptions  found
• He was a bachelor king, that is why he was known as Kumar Bhaskar Varman.

The      dynastic       line       from       Pushyavarman       first       appear       in       the       7th       century, in Dubi and Nidhanpur copperplate      inscriptions      issued      by      Bhaskaravarman      and       in the Harshacharita  The Dubi   copperplate   inscriptions are  the  inscriptions   of   a  grant   issued by Bhaskaravarman of Kamarupa. This is the earliest of all copper plate grants issued by Kamarupa kings discovered so far. This was an issue after an earlier charter, issued by Mahabhuti Varman , was destroyed. All six plates in this grant were first discovered around 1950 during digging near a Siva temple in Dubi village about three miles from the Pathshala railway station, Kamrup district.These plates are currently in the Assam  State  Museum.This  plate  was  issued  before the Nidhanpur copperplate inscription, during the earlier part of Bhaskkaravarman’s reign.

The Nidhanpur copperplate inscription of the 7th century Kamarupa king Bhaskaravarman gives a detailed account of land grants given to Brahmins.

The copper plates were discovered on 29 December 1912, in the village of Nidhanpur in Panchakhanda near what is now Sylhet in Bangladesh. The copper plates were found mostly in Panchakhanda pargana where historians opined that actual granted lands are located. The inscriptions recorded by Bhaskaravarman in different parts of India provide a detailed account of his rule and associate events.

It was customary among the kings of Kamarupa to issue seals for every major event related to the kingdom be they giving land grants to Brahmins or winning a war.

Hiuen Tsang

• Chinese traveler Hiuen Tsang came to India around 630 AD
• Around 643 AD, during the Bhaskar Varman reign, Hiuen Tsang visited Kamrupa and remained in his court for some time.
• He compiled his accounts in his book ‗Si-Yu-Ki‘

The account of Hiuen  Tsang  provides  various  insight  on  the  socio-economic  and  geographical features of the kingdom of Kamrupa. In his account, he mentions about the language spoken being different from north India, People  worshipped  to  Devas  and  performed  sacrifices  and  the  Hindus were divided into many sects. There was minimum following of Buddhism at that period.

Salasthambha Dynasty (c. 650 – c. 900)

The Salasthambha dynasty was the next in line which began with the reign of a chieftain called Salasthambha.The Salasthambha dynasty is also called Mlechchha dynasty.  The Mlechchha dynasty ruled Kamarupa from  their  capital  at  Harruppesvar  (Dah   Parvatiya)   in   the   present day Tezpur, Assam.

According  to historical records, there were twenty one rulers in this  dynasty,  but  the line  is  obscure and the names of some intervening rulers are  not known. Mleccha may be sanskritized form of tribal name  mech  Suniti  Kumar   Chatterji  claims   that   Salastambha   (650-675)   was   a Bodo-Kachari chief of Mech (Sanskritized as Mleccha). According to some historians, the  remnant  of  the  Mlechchha kingdom formed the later Kachari kingdom.

Among all the kings of the Salasthambha dynasty, it was Shri Harshadeva (725-750 AD) who acquitted himself as a good king. His kingdom extended upto Gaur (North Bengal),  Orissa, Kalinga and Kushal (North Bihar).

Another Great King of this dynasty was Harjjaravarman. He was the first in this dynasty to get the throne in vedic rituals.He established the capital at Harupeswar (Tezpur). According to some historians, the remnant of the Mlechchha kingdom formed the later Kachari kingdom.

Pala Dynasty (c 990 – 1138AD)

Brahmapala (990-1010 AD) was the founder of Pala Dynasty.Ratnapala (1010 -1040 AD), the son of Brahmapala was the most famous king of this dynasty. Jayapala (1120-1138 AD) was the last ruler of this dynasty.

Rulers of Pala Dynasty

Important Rulers
Ratna pal

He was the most famous King and great administrator. He shifted the capital  to  Guwahati  and named it Shri Durjoya. He took the title of Maharajadhiraja (Similar to Varman and thus try to establish legitimacy)

Dharmapal

He may have shifted the capital to North Guwahati.The Pala dynasty came to  an  end  when Kamarupa was invaded by the Gaur king of Bengal – Ramapala (c. 1072-1126).

Timgyadeva was made the governor of Kamarupa who ruled between 1110 and 1126 AD. Timgyadeva threw off the yoke of the Pala king and ruled independently for some years when he was attacked and replaced by Baidyadeva under Ramapala’s son Kumarapala.Baidyadeva, who ruled  between 1126 and 1140 AD, declared independence within four years of his rule after the death of Kumarapala. Both Timgyadeva and Baidyadeva issued grants in the style of the Kamarupa kings (three copper plates attached to the seal of the Kamarupa kings by a ring). The work of the pala dynasty of Kamarupa is reflected in the Madan Kamdev sculpture.

Kamrupa Kings after Palas (1138-1440 AD)

After the Pala Dynasty ended, Kings such as Bhingadev, Baidyadeva, Rayridev, Uday Karna and Balladeva and Prithu ruled over kamrupa.During the reign of Prithu, in 1206 and 1226, Bengal Sultanate Mohammad Ibn Bakhtiyar invaded Kamrupa.In 1228, Delhi Sulatanate Illtutmish killed Prithu. With the collapse of Pala Dynasty of Kamrupa, ancient history of Assam ended.

Various Kings ruling different parts of kamarupa after collapse of Palas

Important Kings ruling different parts of kamarupa after collapse of Palas

• Baidyadev
• Prithu
• Sandhya
• Durlabhnarayan
• Arimatta/Sasanka