reforms [i.e. the movements toward Jewish emancipation] following the Enlightenment." In the 18th century, Yiddish was declining in German-speaking regions, as Jews were acculturating, the Haskalah opposed the use of Yiddish, and preference for German grew. By the end of the 18th century, Western Yiddish was mostly out of use, though some speakers were discovered in these regions as late as the mid-20th century. Eastern Yiddish Eastern Yiddish is split into Northern and Southern dialects. Northern / Yiddish ( or "Lithuanian" Yiddish) was spoken in modern-day Lithuania, Belarus, Latvia, and portions of northeastern Poland, northern and eastern Ukraine, and western Russia. Hiberno-Yiddish spoken by Jews in Ireland is based on this dialect. The dialects are again subdivided: Yiddish (, or "Polish" Yiddish) was spoken in Poland, western Galicia (), and much of Hungary. Yiddish ( or "Ukrainian" Yiddish) was spoken in Volhynia (), Podolia (), and Bessarabia (, in Romania). Ukrainian Yiddish was the basis for standard theatre Yiddish, while Lithuanian Yiddish was the basis of standard literary and academic Yiddish. About three-quarters of contemporary Yiddish speakers speak Southern Yiddish varieties, the majority speaking Polish Yiddish. Most Hasidic communities use southern dialects, with the exception of Chabad which uses ; many Haredim in Jerusalem also preserve Litvish Yiddish. In addition to Russian, Jews who settled in Udmurtia would develop dialects incorporating Udmurt and Tatar vocabulary ( or "Udmurt" Yiddish). The Udmurt dialect has been traditionally split into two groupings. dialects, which were centered around Izhevsk, Sarapul, and Votkinsk. dialects, which were centered around Kambarka, Alnashi, Agryz and Naberezhnye Chelny. Differences between dialects The primary differences between the contemporary dialects are in the quality of stressed vowels, though there are also differences in morphology, lexicon, and grammar. Northern dialects are more conservative in vowel quality, while southern dialects have preserved vowel quantity distinctions. Comparison Stressed vowels in the Yiddish dialects may be understood by considering their common origins in the Proto-Yiddish sound system. Yiddish linguistic scholarship uses a system developed by M. Weinreich (1960) to indicate the descendent diaphonemes of the Proto-Yiddish stressed vowels. Each Proto-Yiddish vowel is given a unique two-digit identifier, and its reflexes use it as a subscript, for example Southeastern o11 is the vowel /o/, descended from Proto-Yiddish */a/. The first digit indicates Proto-Yiddish quality (1-=*[a], 2-=*[e], 3-=*[i], 4-=*[o], 5-=*[u]), and the second refers to quantity or diphthongization (-1=short, -2=long, -3=short but lengthened early in the history