The more well-known of these was Burna-Buriash II, ruling ca. 1359 – 1333 BC (short chronology) according to the high chronology of the Kassite Dynasty. He was a contemporary of the Egyptian Pharaoh Akhenaten. The diplomatic correspondence between the two kings is preserved in the Amarna letters. The relationship between Babylon and Egypt during his reign was friendly at the start, and a marriage alliance was in the making. Later in his reign the Assyrian king Ashur-uballit I was received at the Egyptian court. This caused a great deal of dismay from Burna-Buriash who claimed the Assyrians were his vassals. Assyria emerged as a great power during his reign, threatening the northern border of the kingdom.