Conversation so far:
Was types of exploration happened before da Gama?
From the earlier part of the 15th century, Portuguese expeditions organized by Prince Henry the Navigator had been reaching down the African coastline, principally in search of west African riches.
Were any riches found?
They had greatly extended Portuguese maritime knowledge, but had little profit to show for the effort.
After Henry's death in 1460.

Question: What happened after Henry's death?
Self-contained rewrite: What happened after Henry's death in 1460?