A relatively small community of Jews, mostly men, came north of the Alps in late Roman times, settling as far west as Paris, but concentrated in the Rhineland. They apparently took converts as wives, and prospered, developing Yiddish language from Hebrew, old French, and lots of German. When the first Crusade was organized in northern France, one of the first things the Crusaders did was slaughter local Jewish communities, driving Jewish refugees east into Poland. The Polish kings of the era encouraged Jewish settlement because it would be good for the economy (it was), and Poland remained a refuge for Jews until the late 17th century. Russia ended up annexing large parts of Poland, gaining a huge Jewish population as a result. In Poland and Russia, Yiddish picked up lots of Slavic loan wo