So much mammoth ivory was left behind in northern Asia that a trade in fossilized mammoth tusks, dating back to the Middle Ages, continues in Russia today.
(So much mammoth ivory; was left; behind; L:in northern Asia) (a trade in fossilized mammoth tusks; dating; back to the Middle Ages) (a trade in fossilized mammoth tusks, dating back to the Middle Ages; continues; L:in Russia; T:today)
So much mammoth ivory a trade in fossilized mammoth tusks a trade in fossilized mammoth tusks, dating back to the Middle Ages
was left dating continues
behind L:in northern Asia
back to the Middle Ages
L:in Russia T:today