This paper introduces the concept of a bottleneck in lentil (Lens culinaris Medikus) in South Asia and then reviews its rupture. South Asia is the largest lentil growing region in the world and where indigenous lentils show a marked lack of variability. This results from its introduction from Afghanistan around 2000 B.C. and it limits breeding progress. Three approaches to widening the genetic base in the region have been tried, namely plant introduction, hybridization and mutation breeding. Introductions from West Asia flower as indigenous material matures. The asynchrony in flowering has isolated the local pilosae ecotype reproductively. However, the introduction of ILL 4605, an early, large-seeded line, has resulted in its release as 'Manserha 89' for wetter areas of Pakistan and its widespread use as a parent in breeding programs in the region. Hybridization between pilosae and exotic germplasm, primarily at International Center for Agricultural Research in the Dry Areas (ICARDA) followed by selection in the sub-continent has resulted in cultivars with improved disease resistance and yield in Bangladesh and Pakistan. Mutation breeding has given new morphological markers and several promising lines. These examples illustrate not only the widening of the genetic base of the lentil in South Asia, but also the evolution of a breeding program of an international center and national programs targeted toward specific adaptation.