An ethnic group can be defined as a group of people sharing common ancestry and many cultural characteristics. It is argued that the modern ethnicities of Africa originated in the colonial period and that pre-colonial socio-cultural boundaries were marked by their flexibility. In the case of The Gambia, the small size of the country, generations of inter-marriage and the unifying force of Islam (90% of Gambians are Muslims) have contributed to the sharing of cultural heritage between peoples of The Gambia. However they can be broadly classified into different major groups. Although it is not possible to tell the historic tribes apart by appearance, each group has it own traditions, language and background.