He has been instrumental in transforming the field of Turcology, which was traditionally more philologically oriented, into a linguistic discipline.
Chief Editor of the four-volume Encyclopedia of Turkic Languages and Linguistics, to be published online in 2022 by Brill.
In 2022 he and Éva Á. Csató published the second revised edition of the standard reference book The Turkic Languages (Routledge).
For many years he was a Professor of Turcology at the Department of Oriental Studies of the Johannes Gutenberg University of Mainz.
In 1966 he took a doctoral degree ("filosofie licentiat") in Turkic Languages at the University of Uppsala with a thesis "Studien zur reichstürkischen Verbalsyntax".