请教一下0208第37题

37. Only with early seventeenth-century observers did the music of the original inhabitants of the United States and Canada entered recorded history.

这里为什么early那里不用加the呢？一般世纪以前都是加the的吧？请大侠指正一下～

inversion.  the whole sentence can be rewritten :

The music of the original inhabitants of the U.S and Canada entered recorded history only with early seveteenth-century observers.

without "the", "early observers" is correct.