A main cause of the trade was the colonies that European countries were starting to develop. In America, for instance, which was a colony of England, there was a demand for many labourers for the sugar, tobacco and cotton plantations. Paid labourers were too expensive, and the indigenous people had largely been wiped out by disease and conflict, so the colonisers turned to Africa to provide cheap labour in the form of slaves.
Plant usually germinate from seeds, when a seed is planted, a tree usually results. Thus, the sentence, 'Indirect rule sowed the seeds for class and ethnic tensions means that, indirect rule was the factor that bring about class and ethnic tension; it is the root cause and reason why class and ethnic tensions occurred. Indirect rule is the one that give birth to class and ethnic tension.<span />
The printing press invented the future, it was the inspiration for devices like the type writer and the key board. Plus the printing press is the reason the production of the bible had a mass spike in production, thus also shaping the future.
I hope this helps.
