Ancient city ruins, north-central Yemen .
The ancient fortified city of Maʾrib was the centre of the pre-Islamic state of Sabaʾ (950–115 BC). It was located on one of the caravan routes between the Mediterranean Sea and the Arabian Peninsula, and it prospered through its trading monopoly on frankincense and myrrh. The ancient Maʾrib Dam was built с 7th cent BC to regulate the waters of the Wadi Sadd; some 1,800 ft (550 m) long, it irrigated more than 4,000 acres (1,600 hectares) and supported a densely settled agricultural region. The dam was destroyed in the 6th century AD.