Gadadhar Singha or Supaatpha (Assamese: স্বৰ্গদেউ গদাধৰ সিংহ, reign 1681–1696) established the rule of the Tungkhungia clan of the Ahom kings that ruled the Ahom kingdom till its climactic end. He was the son of Gobar Roja, a descendant of Suhungmung, and who had become the king for a mere 20 days. Previously known as Gadapani, Gadadhar Singha was able to stabilize the kingdom after the decade long turmoil following the Ahom victory in the Battle of Saraighat. This period saw the ruthless power grab of Debera Borbarua and Laluksola Borphukan's abandonment of Guwahati and oppression via Sulikphaa Lora Roja. Gadadhar Singha retook Guwahati from the Mughals for good, and established a strong rule of 'blood and iron'. He came into conflict with the Vaishnava sattra and made way for Rudra Singha, his son and succeeding king, to take the kingdom to its zenith.
Gadadhar Singha made his capital at Barkola.
Gadadhar Singha, known as Langi Gadapani, was the son of Gobar Gohain who was made the king by Debera Borbarua in 1675. Gobar Raja was the king for only 20 days and was executed after the fall of Debera Borbarua at the hands of the forces of Atan Burhagohain. After Laluk Sola Borphukan had Atan Burhagohain murdered in 1679, he installed Sulikphaa Lora Roja as the king and tried to become the de jure ruler of the Ahom kingdom. He began a campaign to inflict wounds on Ahom princes who were eligible for the throne. To escape this, Gadapani had to become a fugitive hiding in the Naga hills. The area that Gadapani had fled, may be some where near present-day Mon district is, that was inhabited by the Konyak Naga. During this time his wife Sati Joymati, was tortured and killed by the henchmen of Sulikphaa and Laluk Sola Borphukan.
Gadapani's stay in the Naga Hills are shrouded in mystery, for not much is known about the 2 years in exile. However, the hills are abound with various lores, folktales and legends about Godadapani. The physical attributes of Gadapani were very robust, charming and very handsome. According to one legend Gadapani, after the death of his wife Jaimoti, he was heartbroken and had, become very brooding. It was during this time that his well wishers in fact married him a Konyak girl Watlong. Sadly though, Watlong while coming down with Gadapani from Konyak territory, died at a place named Naginimora while delivering a child. During his time in exhile his Naga friends had got him married to a very beautiful girl Zinyu. Noted Historian and Litterateur Padmanath Gohain Baruah first characterised a Naga girl Dalimi, in his play Joymati. It was shown that it was this girl that Gadapani had come into contact while he was in exhile. Rup Konwar Jyoti Prasad Agarwala's First Assamese Film also showed Dalimi, as a daughter of Naga chieftain who had fallen for the charms of Gadapani.