Timbuktu is a name that has passed into English vernacular as a byword for inaccessibility and remoteness. It is, however, neither of these things owing to the magnificent camel caravans (some of them comprising over 3000 animals) which arrive every year from the Taoudenni salt mines to distribute their produce throughout the Sahel. By the 15th century, Timbuktu was the center of a lucrative trade in salt and gold, straddling the trans-Saharan caravan routes, as well as being a great center of Islamic learning. Much of this ancient city is in decay, but it is the site of many beautiful mosques (Djingerebur, Sankore and Sidi Yahaya for example) and tombs, some dating back to the 14th century.