On the Venetian side, following Süleyman's preoccupation with affairs in Anatolia from 1406 on, relations worsened, as the local frontier warlords were left free to act, while Venice too became entangled in a war of expansion against the local Christian ruler Balša III, an Ottoman vassal, in the western Balkans. Venice sent repeated embassies to Süleyman in 1406–1409 to little avail. During this period, the Venetians negotiated directly with Pasha Yiğit Bey, ruler of Skopje, as well as with Süleyman.[31] Nevertheless, the Venetian ambassador Francesco Giustinian managed to conclude a treaty with Süleyman in 1409, and following the latter's downfall, a similar treaty, the Treaty of Selymbria, was concluded with Musa in September 1411.[32]