White Croats
It is considered that the Czech-Polish Croatian tribes were related to the Croatian tribes from Zakarpattia and Prykarpattia in Ukraine. They became separated during the migration period and seemingly formed one large Proto-Slavic tribe. It is theorized that the migration of those (White) Croatian tribes in the 7th century was the second and final Slavic migratory wave to the Balkans, which is related to the thesis by Bogo Grafenauer about the double migration of Slavs. According to this thesis, although it is possible that some Croatian tribes were present among Slavs in the first Slavic-Avar wave in the 6th century, it is argued that the Croatian migration in the second wave probably was not equally numerous to make a significant common-linguistical influence, while others considered they arrived in a significantly larger number. Zdenko Vinski and argued that the double migration thesis is supported by the rare findings of objects and ceramics of Prague-Korchak culture on the territory of Croatia, Bosnia and Herzegovina, and Serbia which were dated to the end of 6th and beginning of the 7th century (indicating first wave Slavs), and did not make a continuity with Slavic archaeological findings from the 8th-9th century, indicating assimilation. The Croatian tribes are also seen as a warrior group who assimilated into already present Slavs. In the territory of present-day Croatia they also gradually assimilated with the Pre-Slavic population because archaeology indicates a significant continuity of late antiquity population which have partially withdrawn to the mountains, coastal cities and islands.
Bunjevci
Disputes over the national status of the Bunjevci go back to the nationalism wave in the 19th century in Austria-Hungary, but their "national status" remained ambiguous since, as the debate revived by the Breakup of Yugoslavia in the 1990s. It has been argued that they are Croats, Serbs, and yet another as a fourth nation of the Kingdom of Serbs, Croats and Slovenes among the South Slavic nations. In the period between 1920 and 1930 and again in 1940, there were three types of manipulation to neutralize their Croatian nationality, primarily emphasizing their ethnic distinctiveness from both the Croats and Serbs, that can be both Croats and Serbs or it's unimportant because both are Yugoslavs, and open denial of their ethnicity and religious belonging considering that Bunjevci and Šokci are Serbs of the Catholic faith. The third was argued by Serbian academic elite, including Aleksa Ivić, Radivoj Simonović, Jovan Erdeljanović among others, but without proper argumentation and ethnological basis, which also included unsubstantiated claims like that they got Ikavian pronunciation because of Franciscan friars influence.