The reasons for African colonisation were mainly economic, political and religious. ... These countries became involved in a race to acquire more territory on the African continent, but this race was open to all European countries. Britain had had some success in halting the slave trade around the shores of Africa
You would use a comma. The semi colon acts when both what is in front and behind it can stand alone as a sentence. “With technology in the hands of so many people” does not make sense standing alone.
