【英语翻译northernchinaover6000kilometers7.5meters(25feet)(average)earthbrickandstone7thcenturyBCkeepoutinvadresvisitedbypeoplefromallovertheworld】
英语翻译
northernchina
over6000kilometers
7.5meters(25feet)(average)
earthbrickandstone
7thcenturyBC
keepoutinvadres
visitedbypeoplefromallovertheworld