From Wiktionary, the free dictionary
From Elbing + -ian.
Elbingian (not comparable)
- (rare) Of or pertaining to Elbing or Elbląg, a city in northern Poland.
1971, William Fiddian Reddaway, The Cambridge History of Poland, volume 1, page 4:[…] with the consent of the King, the Prussian army again occupied Elbingian territory with the exception of the town itself.