Croatia has for a long time been occupied by foreign empires or kingdoms. Despite (and thanks to) that fact, Croatia is a hub of languages, many of which are native to its lands.
Minority languages which are sometimes considered dialects have multiple possible answers
Some notes: This has by far been the hardest map for me to make because I had to do lots of extra research in order to provide a most accurate map. Istriot is spoken by only about 500 people in a few cities in the highlighted area on the map. Same goes with Istro-Romanian, only having a few hundred speakers in the highlighted area. Some approximations were made to accommodate that as there are no official maps demarcating where Istriot and Istro-Romanian are spoken (at least from these past few centuries). Finally on the Croatian 'dialects', these seem to be called dialects for purely political reasons as mutual intelligibility between the three is limited. This is especially true for Kajkavian which is actually more closely related to Slovene than standard Croatian (which would make up for the fact that there is no Slovene spillover into Croatia). The Shtokavian dialect of Croatian (actually Serbo-Croatian) is the one which the standards for Croatian, Serbian and Bosnian are based on.