Michel Kuršanskis explains that this unsuccessful siege was in response to the Trapezuntine ally, Queen Tamar of Georgia, who had attempted to capture Erzurum in 1205, but failed. When Sultan Kaykhusraw began his punitive campaign against Trebizond, he found his route limited to a few passes in the Pontic Alps where his forces harassed by the locals. Further, Alexios could respond to his attacks by "closing the sea" to all merchants, who could neither travel to the Crimea nor return from there.