History of the driver's side
“In the past, almost everybody travelled on the left side of the road because that was the most sensible option for feudal, violent societies. Since most people are right-handed, swordsmen preferred to keep to the left in order to have their right arm nearer to an opponent and their scabbard further from him.”
And:
“Pakistan also considered changing to the right in the 1960s, but ultimately decided not to do it. The main argument against the shift was that camel trains often drove through the night while their drivers were dozing. The difficulty in teaching old camels new tricks was decisive in forcing Pakistan to reject the change.”