Susenghphaa (reign 1603–1641), also Pratap Sinha (Singha) (Assamese: স্বৰ্গদেউ প্ৰতাপ সিংহ ), was the 17th and one of the most prominent kings of the Ahom kingdom. As he was advanced in years when he became king, he is also called the Burha Raja (Old king). His reign saw an expansion of the Ahom kingdom to the west, the beginning of the Ahom-Mughal conflicts, and a reorganization of the kingdom with an expanded Paik system and reoriented village economy designed by Momai Tamuli Borbarua. His expansion to the west is underlined by the two new offices that he created: that of the Borbarua and the Borphukan. The alliances he formed with the rulers of Koch Hajo resulted in formation that successfully thwarted Mughal expansion. The administrative structure that he created survived till the end of the Ahom kingdom in 1826.
After the death of Sukhamphaa in 1603, his son Langi Gohain, was installed as the Swargadeo by the ministers Tonkham Borgohain, Chaopet Burhagohain and Banjangi Borpatrogohain. At his coronation he was 58 and he assumed the name Susenghphaa accorded to him by the Tai priests. He accepted an offer of marriage to the Jaintia princess and the subsequent events brought him into conflict with the Kachari kingdom. He also established alliance with the Koch Hajo rulers by marrying Mangaldahi, the daughter of Parikshit Narayan, in 1608.
According to historian Late Benudhar Sarma, the present form of worship of Durga with earthen idol in Assam was started during the reign of King Susenghphaa or Pratap Sinha. The King heard about the festivity, the pomp and grandeur with which the King Naranarayan of Koch Bihar celebrated Durga Puja from one Sondar Gohain, who was held captive by the Koch Raja. King Pratap Sinha sent artisans to Koch Bihar to learn the art of idol making. The King organised the first such Durga Puja celebration in Bhatiapara near Sibsagar. This was the first time Durga Puja with earthen idols in Assam was held for the masses, in addition to the worship in Durga temples.