text: According to Mijo Lončarić (1988), the formation of the Proto-Kajkavian linguistic and territorial unit would be around the 10th century (when it separated from Southwestern Slavic), until the 12th century it is a separate node of Croatian-Serbian language family (excluding Slovene), between the 13th and 15th century when formed as a dialect with main features known today, until the end of the 17th century when lost a part of spoken territory (to the South, Southeast and especially to East in Slavonia), and from the 17th-18th century till present time when regained part of lost territory by forming new transitional dialects.
  Characteristics
  The Kajkavian speech area borders in the northwest on the Slovene language and in the northeast on the Hungarian language. In the east and southeast it is bordered by Shtokavian dialects roughly along a line that used to serve as the border between Civil Croatia and the Habsburg Military Frontier. Finally, in the southwest, it borders Chakavian along the Kupa and Dobra rivers. It is thought by M. Lončarić that historically these borders extended further to the south and east, for example, the eastern border is thought to have extended at least well into modern-day Slavonia to the area around the town of Pakrac and Slatina, while East of it transitional Kajkavian-Shtokavian dialects. The transitional dialects during Ottoman invasion and migrations almost completely vanished.