穿越撒哈拉沙漠的骆驼商队曾经是重要的贸易纽带。

The ___Trans-Saharan camel caravans were once vital trade links.

跨撒哈拉贸易在古代连接了北非和西非的文明。

___Trans-Saharan trade routes connected civilizations in North and West Africa in ancient times.