Brassica juncea has been evolved after hybridization between

Brassica Juncea is a variety of mustard seeds, commonly known as Brown mustard, Chinese mustard, Indian Mustard, etc.
It is an amphidiploid with a chromosome number of 18. It evolved after hybridization between B. nigra (n = 8) and B. compestris (n = 10). The type of hybridization is natural interspecific hybridization.