Lets say we have an homogeneous population with same language and accent.
Took about 10 % of this population and send them to colonize a far away virgin territory, within a few generation, they will develop their own different accent ( different then their home country ).
Took about 10 % of this population and send them to colonize a far away virgin territory, within a few generation, they will develop their own different accent ( different then their home country ).