Complex sentence: Historically, Mouhot is usually credited with "discovering" Angkor, but local Khmers had always known of its existence and location, and other European explorers and missionaries such as Portuguese monk Antonio da Magdalena had already visited Angkor Wat and written about it in 1586.
Split into simpler sentences: Historically, Mouhot is usually credited with "discovering" Angkor, but local Khmers had always known of its existence and location. Other European explorers and missionaries such as the Portuguese monk Antonio da Magdalena had already visited Angkor Wat and written about it in 1586.