57.占地……面积 cover　 a vast area of

56.属于　　 belong to

55.热情接待 warmly receive them

54.挖出　　 dig up

53.据信　　 It is believed that

52.与……有贸易交流have trade link with

51.提醒某人某物 remind sb of sth

50.古代　　 in ancient times

49.充当　　 serve as

48.(也)不有大量的象牙

as well as a large quantity of ivory