In the 19th and 18th centuries BC, merchants from Assur in Assyria established a trading post there, setting up in their own separate quarter of the city.
The deaths of both Suppiluliuma and his immediate successor Arnuwanda II might be seen as an indirect result of the Zannanza affair because both succumbed to a plague brought to Hattusa by the prisoners from Amqu.
In the Amarna letters, Amenhotep III wrote to the Arzawan king Tarhunta-Radu that the "country Hattusa" was obliterated, and further asked for Arzawa to send him some of these Kaska people of whom he had heard.