With no written records, historians can only wonder why the Incas built such a mysterious place.

由于没有任何文字记录，历史学家们只能对为何印加人建造出如此神奇的地方而感到惊讶了。

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Travelling families, with no written records and with hidden traditions, simply vanished.

ECONOMIST: Europe��s spectral nation

They also help to rebut the notion that sub-Saharan Africa produced only oral histories, with little or no written records.

BBC: Timbuktu��s treasure trove of African history