Brahmaputra valley from north Burma and established a kingdom in its
eastern region in the early 13th century. The founder of the ruling dynasty
was Sukhapha. But it was during the reign of Sukhangpha that territorial
expansion was done at the expense of the neighbouring kingdom of Kamata.
During the reign of Sudangpha in the early 15th century the influence of
brahmanical Hinduism began to gain ground in Ahom society. The greatest
Ahom king was Suhungmung (1497–1539) who suppressed the Chutiyas and
Cacharis and repelled the successive invasions of the Sultans of Bengal,
including that of Ala-ud-din Hussain Shah. His reign is also remarkable not
only for the rapid Hinduisation of the Ahoms (he assumed the Hindu name of
Svarga Narayan), but also for the spread of a reformed Vaishnava doctrine
associated with the name Sankaradeva.
    The Ahom kingdom, geographically isolated and politically cut off from
north India by the independent sultanate of Bengal, did not join the
mainstream of Indian history till the 17th century when it became the target
of Mughal invasions. But its history is of special interest for three reasons:
The Ahoms introduced into the Indian population a new racial element. They
brought with them their religion, social customs and also political and
military system.
They gradually succumbed to brahmanical Hindusim and adopted its
religious and social teachings to a large extent.
The Ahom historical chronicles, known as Burangis, have no counterpart in
the regional languages of north India.
Orissa
Eastern Gangas
Anantavarman Choda Ganga (1076–1148) made Orissa a powerful kingdom
by extending its territories from the mouth of the Gangas in Bengal to that of
the Godavari in the south. Besides being a valiant soldier and conqueror, he
was a patron of religion and of Sanskrit and Telugu literature. He built the
famous Lingaraja temple at Bhuvanesvar and the Jagannatha temple at Puri.
The next notable ruler of Orissa was Narasimha I (123–864), who occupied a
part of Bengal from its Muslim rulers. He built the famous Sun temple at
Konark. With his death came the end of the glory of the Eastern Ganga