The historic Kashan bazaar in central Iran once sat on a major caravan route, its silk carpets known the world over. But for the weavers trying to sell their rugs under its ancient arches, their world has unravelled since the collapse of Iran’s nuclear deal with world powers and wider tensions with the West. Rug exports, which exceeded $2 billion (€1.86 billion) two decades ago, have plummeted to less than $50 million (€46.5 million) in the last year that ended in March, according to government customs figures. With fewer tourists coming and increasing difficulties in making international tran…