After the Balkan Wars (1912–1913) the Slavs in Macedonia were regarded as southern Serbs and the language they spoke a southern Serbian dialect. Despite their attempts of forceful assimilation, Serb colonists in Vardar Macedonia numbered only 100,000 by 1942, so there was not that colonization and expulsion as in Greek Macedonia. Ethnic cleansing was unlikely in Serbia, Bulgarians were given to sign declaration for being Serbs since ancient times, those who refused to sign faced assimilation through terror, while Muslims faced similar discrimination. However, in 1913 Bulgarian revolts broke out in Tikvesh, Negotino, Kavadarci, Vartash, Ohrid, Debar and Struga, and more than 260 villages were burnt down. Serbian officials are documented to have buried alive three Bulgarian civilians from Pehčevo then. Bulgarians were forced to sign a petition "Declare yourself a Serb or die." 90,000 Serbian troops were deployed in Macedonia to keep down resistance from Serbianization, Serbian colonists were unsuccessfully encouraged to immigrate with the slogan "for the good of Serbs", but the Albanians and Turks to emigrate. In the next centuries, a sense of a distinct Macedonian nation emerged partly as a result of the resistance of IMRO, despite it was split into one Macedonist and one pro-Bulgarian wing. In 1918 the use of Bulgarian and Macedonian language was prohibited in Serbian Macedonia.