Silesian
1.250.000 speakers
20 language specific characters
ISO 639 code: szl
Silesian or Upper Silesian is a West Slavonic language with about 1,250,000 speakers in Upper Silesia, a region that is partly in Poland and partly in the Czech Republic. Silesian is closely related to Polish and is considered a dialect of that language by some linguists.
A new Silesian alphabet was created in 2006 and is widely used on the internet and also on the Silesian Wikipedia.
Silesian is used to some extent in literature, films, radio and television and newspapers. Although the language currently has no official status, move are being made to change this.
source
wikipedia.org, omniglot.com & ethnologue.com
sample text

Niy bydź szwalba jeli żeś słowik.Niy bydź słowik ani dziambel jeli żeś pjes. Ale szuszczyć kożdy może. My som Underware.

translation kindly provided by Adam Twardoch