Whether the Natchez were more unreceptive to Gallic ways than
were neighboring Indians is moot, but certainly the French encountered
in them a atrong and unusual tribe.
我看不懂的是下面这句
were more unreceptive to Gallic ways than were neighboring Indians...
than 后面为什么还有be 动词 were

than (the Natchez) were neighboring...

我觉得应该是倒装 Natchez是否比临近的indians更排斥高卢人传教是有争议的 但那群法国人一定遇到了(Natchez中很强大特别的一支部落