_________ at the foot of Helan Mountain , the royal tombs of Xixia Mausoleum (西夏王陵)___________ about 900 years ago are known as Oriental (东方的) Pyramids .
_________ at the foot of Helan Mountain , the royal tombs of Xixia Mausoleum (西夏王陵)___________ about 900 years ago are known as Oriental (东方的) Pyramids .