The small actors playing the Munchkin roles weren't strangers to one another, assembled from wherever the producers could find them. They'd actually all been performing together for years, and were a performance troupe from Europe called the Singer Midgets, after their manager Leo Singer.
They were, as we've said, paid less than Toto, and their meager salary may actually have been reduced further; Singer handled the payments for them and some sources say he kept most of the money for himself. A number of the troupe were German or Bavarian and were very glad to be working in the United States because it took them away from the rise of Nazism at home. Most of them spoke no English at all, and so scenes where the Munchkins are seen speaking or singing are all actually dubbed.