The primary centre of origin of cultivars of Malus is within the region of Asia Minor, the Caucasus, central Asia, Himalayan India and Pakistan and western China, in which at least 25 native species of Malus occur. The Old Silk Road from the Black Sea to western China played an important role in the evolution of the cultivated apple. Travellers on foot and camel and pack-horse trains must have traversed it since Neolithic times. The animals would eat all manner of fruit, and seeds of diverse species of Malus would have been scattered, in a fertile medium, along the way. The possibilities for hybridisation between previously isolated species would have been legion. It seems that M. sieversii, the fruit of which ranges from small to large, played a seminal role in the origin of the cultivated apple. To the east it could have hybridised with M. prunifolia, M. baccata, and M. sieboldii, and to the west with M. turkmenorum and M. sylvestris. Selected cultivars, from random hybridisations and disseminated through grafting, were probably well-established in the cilivisations of the near east by 4,000 BC and were lated documented by Roman authors. Thereafter, the apple cultivars in Western Europe were more or less cut off from their parental origins and evolved in relative isolation. A project has been established to study the relationships of Malus species, and to determine which species have contributed to the gene pool of the cultivated apple. Analysis of chloroplast and nuclear DNA sequences will be important sources of data.