Mezue ahịrịokwu na-esonụ: Naanị ọnwa ole na ole ka ọ rịgoro n'ocheeze nke Ivan Shishman, na 26 Septemba 1371, ndị Ottoman ndị Turkey meriri nnukwu ndị agha Ndị Kraịst nke ụmụnne Serbia bụ Vukašin Mrnjavčević na Jovan Uglješa na
Agha Chernomen. Ọ bụ ezie na Uglješa gbalịrị ịmepụta njikọ sara mbara nke ga-agụnye Bulgaria, Ivan Shishman, onye kwesịrị iwusi ikike nke ya ike, esonyeghị. Mgbe ndị Turkey merisịrị n'agha Chernomen, ha lụsoro ndị Bulgaria ọgụ ozugbo. Ottoman sultan Murad m manyere Ivan Shishman ịlaghachi n'ebe ugwu nke Ugwu Balkan ma merie ugwu Thrace, Rhodopes, Kostenets, Ihtiman na Samokov. N'enweghị ike iguzogide mwakpo ndị ahụ, Ivan Shishman aghaghị iso ndị Ottoman kwurịta okwu na 1373. A manyere ya ịghọ onye Ottoman na ikwe ka nwanne ya nwanyị Kera Tamara, onye ama ama maka ịma mma ya, bụrụ nwunye Murad nke Mbụ. N'okpuru nkwekọrịta a, Bulgaria nwetaghachiri ụfọdụ mpaghara ndị meriri dị ka Ihtiman na Samokov, wee malite ihe fọrọ nke nta ka ọ bụrụ afọ iri nke udo na-adịghị mma na ndị Turkey. N'agbanyeghị vassalage na nkwekọrịta udo, mwakpo ndị Ottoman ka emegharịrị na mbido 1380s wee kwụsị na 1385 na ọdịda nke Sofia, ebe ikpeazụ nke Ivan Shishman na ndịda nke Ugwu Balkan.