text: In its almost thousand years, Chakavian has undergone many phonetic, morphological, and syntactical changes -- chiefly in the turbulent mainlands, but less in isolated islands. The problem with classifying Chakavian within Western South Slavic stems in part from there being no unanimous opinion on the set of traits a dialect has to possess to be classified as Chakavian (usually argued only as a gradation of "Chakavism"). Its sub-dialects have various differences but also closeness to neighboring Shtokavian and Kajkavian speeches, and all three dialects are part of a dialect continuum, while their diversification into dialects and languages is mostly political, ethnic and symbolic. From a linguistic point of view, national and other names based on interrogatory pronouns are practical, but also inaccurate as dialect/language definitions; linguists would more precisely replace these with complex isoglosses in the dialect continuum.
  Dialectologists and Slavists maintain that when the separation of Western South Slavic speeches happened, they separated into five divergent groups, more specifically two, one Slovene and second Serbo-Croatian with four divergent groups - Kajkavian, Chakavian, Western Shtokavian and Eastern Shtokavian. The latter group can be additionally divided into first (Kajkavian, Chakavian, Western Shtokavian) and second (Eastern Shtokavian, Torlakian). According to isoglosses, and presumed end of existence of the Southwestern Slavic around the 8th-9th century, the formation of the assumed Proto-Chakavian linguistic and territorial unit would be around the 9th-10th century (when it and Proto-Western Shtokavian separated), while of the Chakavian dialect known today between the 12th-16th century.