IN THE LAST DAYS of Ivan Assen’s rule, the threat of a Tartar invasion loomed over Bulgaria. His underage sons Koloman and Mihail II Assen, from his first and second marriage respectively, ascended the throne one after the other, and failed to repulse the Tartar onslaught from the north. With internal peace shattered by boyars’ unrest, the hard-gained prosperity of Ivan Assen II was dwindling quickly. The Nicean Empire occupied lands in Macedonia and the Rhodopes. The Comnenus family took away Epirus and Albania, while the Hungarian king seized Belgrade and Branichevo.