Perhaps you should try some spelling variations:
"slave trade / test indies, british" » "slave trade / west indies, british", "slave trade / test induces, british", "slave trade / test index, british"
"slave trade / east indies, british" » "slave trade / east india, british", "slave trade / west indies, british"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"slave trade / test indies, british\") OR (\"slave trade / east indies, british\"))*".
• Removing quotes may allow a broader search: (( slave trade / test indies, british ) OR ( slave trade / east indies, british ))*.