After the major Bulgarian success in the battle of Tryavna in 1190 their troops launched frequent attacks on Thrace and Macedonia to liberate all Bulgarian lands. The Byzantines could not face the fast Bulgarian cavalry which attacked from different directions on a vast area. Towards 1194 Ivan Asen I had taken the important city of Sofia and the surrounding areas as well as the upper valley of the Struma River from where his armies advanced deep into Macedonia.