1. In 895 the Bohemia / Moravia (including Silesia at that time) princes came to Regensburg of Frankish and Holy Roman Empire and pledged allegiance to German emperor Arnulf of Carinthia .
2. 622-662 first Slavs in Europe are the Moravians under Frankish ruler Samo.
3. Mieszko I was first duke of a Poland seperat from Czech (formerly Czech and Lech)Mieszko I and son Boleslaw I Chrobry (as well as later Polish rulers pledged allegiance to emperor in turn for receiving land on loan (landlien) to rule over.
4.The Polish Piast rulers died out in 1370. (Imperial law, when a ruling house dies out , the land reverts back to the empire.
5. In circa 1537 Brandenburg Hohenzollernrulers made an agreement with the Silesian German Piasts, that Brandenburg would inherit Silesia rule. Emperor did not permit it, because the emperor (Maximilian I) had made an agreement in 1515 with Polish and Hungary ruler .Maximilian adopted Luis of Hungary.
6. Crossen , Or Krossen district (Schwiebus referred to in above website as 1815) including Zuellichau came under Brandenburg rule in 1472.
Are you sure about etymology of name Silesia ? It seems too similar to its Polish name Śl&aogonek;sk which is of clearly different etymology (from Mount Śl&eogonek'&zdotabove;a)
There are many other geographical Polish names that were latinized with ending -ia, and there was either a short vocative e/i vowel (vocal yer) between first two consonants or second consonant was a vocal l, which sounds like el/il, so s(short i)l(something that sounds like on)sk(short e)/s(short i)l(something that sounds like nasal e)(hard vocative z)- -> silesia seems very likely.
Sorry, but your etymology sounds like some German propaganda. --Taw
Generally there is no such consonant pair in old Polish as /(soft S)L/. But in Polish 'short soft e/i' and 'short hard e/i' (these two letters exist in Russian spelling as soft yer and hard yer, but they aren't pronounced) become silent in most positions. So it was probably /S(short soft e/i)L(nasal E)(hard Z)-/. Usual way of latinization at that times were taking local name (which was only spoken, national languages weren't written at that time), write in to be pronounciable in Latin, and append grammatically-correct suffix. This suffix was often '-ia', as in (Mazowsze -> Mazovia, Kalisz -> Kalisia, Warszawa -> Varsovia). Also because Latin had no letter for nasal E and hard Z, they were written as E and S. So natural latinization was 'S?LESIA'. The last problem is what has happened to short soft e/i. It could be any of E I or nothing. At that time short vowels were pronounced, so nothig wouldn't be very probabe. I don't know why it became I and not E. That might have been feature of local dialect or something like that. Anyway 'SILESIA/SELESIA' is clearly Latin encoding of Polish name of this tribe and region.
I've never heard anything about this Silinger tribe. I think that I would if their existence and name were generally accepted, because I live here. --Taw