I have a problem with collocations. I need to say "Slaves were unloaded on these coasts", but I don't know if "unload" is the correct word for "slaves". Moreover, I'm not sure about the preposition. Is it "on the coast" or "in the coast"?
I think "unload" is fine. Normally you wouldn't use it when talking about people but I think it's appropriate since slaves were just another cargo to the slavers.
"On the coast" is correct, not "in the coast".
The following ngram shows that 'unload slaves' has been used in published writings.
You can click on the links at the bottom of the page to read excerpts from the texts.
An examination of the numbers shows that the collocation is not common.
I find it interesting that, according to that corpus, the term is exclusively used after the abolition of slavery. I wonder what was used when slavery was in progress. I presume there was another term.