The Manapa-Tarhunta letter (CTH 191; KUB 19.5 + KBo 19.79) is a Hittite letter discovered in the 1980s. It was written by a client king called Manapa-Tarhunta to an unnamed Hittite king around 1295 BCE.
The only datable Manapa-Tarhunta was the one who became undisputed king of Seha River around the time of the death of Arnuwanda II (1322 BCE). This letter further mentions a Kupanta-Kurunta. A treaty between Mursili II (1322-1295 BCE) and a Kupanta-Kurunta, who is king of Mira (Western Asia Minor), survives which mentions this Manapa-Tarhunta as still alive.
The letter also mentions a "Piyama-Radu", an "Atpa" (King of Miletus according to the Tawagalawa letter), and an attack on Hatti's historic ally Wilusa. These figures and events associate the Manapa-Tarhunta letter with an early stage of the events mentioned in the Tawagalawa letter (c. 1250 BCE). The Tawagalawa in that letter was the brother of Ahhiyawa's king, and is identified as the legendary Eteocles who lived a generation before the Trojan War. No king of Ahhiyawa is on record before Mursili's reign; at most there might have been a "man from Ahhiya" as under Arnuwanda I (1400-1360 BCE).
Manapa-Tarhunta had passed on the succession to Manapa-Kurunta (presumably Tarhunta's son) by the time of the treaty between Muwatalli II (1295-1272 BCE) and Alaksandu of Wilusa. The Manapa-Tarhunta letter would then have been written in the later years of Mursili or else the earlier years of Muwatalli II.
Piyama-Radu is further mentioned, as a past figure, in the Milawata letter (c. 1225 BCE); which like the other two letters handles the aftermath of events in Wilusa which did not go the Hittites' way.
The Manapa-Tarhunta letter mentions first an attack on Wilusa, and then how a notorious local troublemaker called Piyama-Radu is harrying the western lands. The Hittite king has apparently ordered Manapa-Tarhunta to drive out Piyama-Radu himself, but Manapa-Tarhunta's attempt has failed, so that a Hittite force is now sent out to deal with the problem. Before marching to Wilusa, the expeditionary force camps at the land near the Seha River, placing Wilusa in the north-west corner of Anatolia.
For Trevor Bryce, this leads to the inescapable conclusion that the location of Wilusa is identical to that of the archeological site of Troy (Illios).