Yaziges & Roxolanes

I wonder about the previous home of the Yaziges.
As far I know, they are known as Yaziges Metanastes= the Emigrants
Yaziges, or Yaziges who changed their home.
Their cousins, the Roxolanes have a "properly name".

Questions:
1)what should mean "Yaziges" and where do we find previous traces of
them before arriving in south of Ukraine?
2) which is the etymology of Roxolanes? Is there to make a link with
"alanes" ?
I tought about the "Royal scythians" and that mybe Rox=rex= royal
+alanes= Roxolanes= The royal alans.
Any thoughts about?