Wheat is one of the most important crops in the world. Its production requires less water than rice or corn, and wheat improvement is urgently needed to respond to the increase of the world’s population. This will be achieved through the introduction of novel genes into wheat. It is very important, therefore, to understand the genetic diversity of relatives of wheat. I examined the genetic diversity of wheat relatives and found that, at present, quite a limited range of diversity is employed in wheat. I also discovered that the distribution of a wild relative of wheat has been greatly affected by post glacial climate changes.