But everybody even you should know that originaly croatians settled primorska hrvatska, that was area of croatian ethnogenesis and from dose places did croatian kingdom expand. Size of Tomislavs kingdom dosent matter to me even it was whole of hungary under Tomislav my post deals with dialect question.
About the slovene dialects i will tell you this way;
Slovenian is not differated by Ča, Što and Kaj. Slovenian standard language is generaly based on all dialects however Gorenjsko (dark green) and Dolenjsko (light green) dialects are main contributors becouse they are in purest forms. Wherever certain slovene dialect had most arhaic slavic word they used it in standard language. Only slovene dialect that is worth mentioning as different from others is Prekmurian (yellow one on your map) and i would give that dialect special rights if i could but i cant.
I ask becouse i belive standard languages should be based on most arhaic dialects and chakavian is belived to be most archaic. Linguist who study arhaic proto-slavic languages usualy study chakavian as well becouse it preserved so much old words and other language rules.
All i want to hear is yay or nay and why? Thats all!!!
I posted official map, what you posted is some low-brow Slovenian map, split between Croatia and Panonia ended in early 9th century, around 820, while we were under Franks.
Štokavian, Čakavian, and Kajkavian are dialects of Croatians.
Some like Kajkavian developed later, and there is also Ikavian, Ijekavian, and Ekavian split in diaelcts.
So for instance you have Gradiščanski Hrvati, which were 14 century emigrants from modern BiH, and they have all those dialect preserved in isolation.
I posted you link where everything is explained, use google translator, no need to thank me.
If you wont short answer, it was because of Venetians