Data for the different regions taken from "Köbler, Gerhard, Althochdeutsches Wörterbuch, (4. Auflage) 1993"; See also: Oldhighgerman Dictionary - University of Innsbruck (german)
All 5 indicated West Germanic language variants have undisputed documents and primary sources. Old Thuringian has no undisputed primary sources and is hence not indicated on the map, but marked as Franconian. Lombardic and Old English aren't indicated either.
Caption in Standard German says the following (from top to bottom):
Borders: Mind that the borders drawn on this map are only approximate. Not enough data has been handed down from the Early Medieval Period to guarantee 100% accuracy for any historic conclusion.
Undisputed primary sources before the year 1000 are, e.g. for:
Файл содержит дополнительные данные, обычно добавляемые цифровыми камерами или сканерами. Если файл после создания редактировался, то некоторые параметры могут не соответствовать текущему изображению.
