1st question: Taghaza (also Teghaza) is an abandoned salt-mining centre located in a salt pan in the desert region of northern Mali. It was an important source of rock salt for West Africa up to the end of the 16th century when it was abandoned and replaced by the salt-pan at Taoudenni which lies 150 km (93 mi) to the southeast.
2nd question: A caravan (from Persian: کاروان) is a group of people traveling together, often on a trade expedition. Caravans were used mainly in desert areas and throughout the Silk Road, where traveling in groups aided in defense against bandits as well as helping to improve economies of scale in trade.
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