He founded the Kamata Kingdom when he moved his capital west to Kamatapur (present-day Gosanimari) sometime after 1257 CE.
[1] He became the ruler of Kamarupa in 1228, when Sultan Nasiruddin Mahmud Shah, who had earlier killed his predecessor Raja Prithu in 1228 AD,[2] However, after Nasir-ud-din Mahmud withdrew from Kamrup, Sandhya stopped paying tribute and assumed independence.
After that, to avenge the previous defeats, he invaded the western border of Gaur (Lakhnauti) and annexed regions across the Karatoya into his kingdom.
In retaliation, Malik Ikhtiyaruddin Yuzbak the governor of Gaur for the Mamluk rulers of Delhi, attempted an invasion on Sandhya's domain in 1257.
However, Sandhya defeated the invasion attempt, captured and killed Malik Ikhtiyaruddin Yuzbak.