Munchkinland

The only thing left in what was supposed to be munchkinland was Dorothy’s house and the crumpled beginning of the yellow brick road. While I assume the munchkins had been turned to stone like everyone else in Oz, I have always wondered why there were no houses or anything left? Considering the munchkins were in the parade at the end they had to have been there somewhere. I know there wasn’t a munchkin City in the book like in the 1939 movie, but there were still munchkin houses scattered around that Dorothy could see when she stepped out of her house after the tornado dropped her. The whole place was trees, and considering Dorothy was only gone 6 months, that wouldn’t have been long enough for trees that big to grow around it. Was there ever any explanation for that?