This book provides an overview of the latest advancements in the field of alien introgression in wheat. The discovery and wide application of molecular genetic techniques including molecular markers, in situ hybridization, and genomics has led to a surge in interspecific and intergeneric hybridization in recent decades. The work begins with the taxonomy of cereals, especially of those species which are potential gene sources for wheat improvement. The text then goes on to cover the origin of wheat, breeding in connection with alien introgressions, and the problems of producing intergeneric hybrids and backcross derivatives. These problems can include crossability, sterility, and unequal chromosome transmission. The work then covers alien introgressions according to the related species used, as well as new results in the field of genomics of wild wheat relatives and introgressions.