Sujinphaa (fl. 1675–1677) or Sur Singha was a Namrupiya king of the Ahom kingdom. Atan Burhagohain installed him on the throne after removing Debera Borbarua from power and deposing the previous king, Gobar Roja. Sujinphaa began his reign well with proper advice and support from Atan Burhagohain and other nobles. But soon, acting on the advice of his wife and other advisors, the king began to defy the authority of the Burhagohain, which resulted in a head-on collision between both sides. The king successfully defended the first onslaught of Atan Burhagohain's forces, but fell to the second, which was reinforced with troops from Guwahati. Sujinphaa was deposed and blinded. Some sources state that he committed suicide, while some sources maintain that he was murdered by Bhatdhara Phukan, the brother of Laluksola Borphukan.
Sujinphaa was the son of Namrupia Raja Tailai and grandson of Ahom king Pratap Singha. His early name was Arjun Konwar and he belonged to the Namrupia branch of Royal Ahom Dynasty. His wife belonged to the Sandikai family, one of the prominent Ahom noble families, who bore him four sons, Sengmung, Dighala, Sutyang and Sunnang. They were also known as Kalia Gohain, Dighala Gohain, Dhala Gohain and Saru Gohain. He, along with his family lived in Dihing, maintaining their family estate.
After the deposition and execution of Udayaditya Singha in 1672, the Ahom kingdom entered into a period of weak kings, with de facto power wielded, successively, by three prominent ministers: Debera Barbarua, Atan Burhgohain and Laluk Sola Borphukan. Debera Borbarua, the first such minister, rose in prominence and exerted complete authority over the administration in Garhgaon, the Ahom capital, at a time when many powerful ministers were at guard at newly occupied Guwahati soon after the Battle of Saraighat (thus these officers were called Saraighatias). Debera's period of control saw three kings being deposed and put to death, within a short period of about three years. After Udayaditya Singha, he installed and subsequently deposed two others: Ramdhwaj Singha and Suhung. He then installed Gobar from Tungkhungia branch of Royal Ahom Dynasty on the throne. Meanwhile, the Saraighatias in Guwahati decided to put an end of Debera's atrocities and therefore led by Prime Minister Atan Burhagohain, they marched towards the capital Garhgaon. Gobar and Debera Borbarua were captured and put to death. The nobles offered the crown to Atan Burhagohain and declared their intention to make him king, but Burhagohain gently declined the offer stating that only members of Royal Ahom Dynasty, the direct descendants of Sukaphaa were alone eligible to become kings. The Burhagohain searched for a suitable candidate for the throne, and they found Arjun Konwar, living at Dihing, suitable for the post. Therefore, Atan Burhagohain nominated Arjun Konwar as the king of the Ahom kingdom. In November 1675 CE, the coronation ceremony took place at Barnaosal at a newly constructed Singarighar, without which function no prince attained the status of a full-fledged sovereign. He assumed the Ahom name Sujinphaa, while the Brahmins conferred on him the title Sur Singha. Owing to his origin from Dihing, he was also known as Dihingia Raja. Sujinphaa ascended the throne with great éclat. Large sum of money were distributed amongst the people and the festivities continued for seven days.