During the same decade, a line was also built from Khartoum southward to Sannar, the heart of the cotton-growing region of Al Jazirah. A westward continuation reached El-Obeid, then the country's second largest city and center of gum arabic production, completed in February 1912.[1] In the north, a branch line was built from near Abu Hamad to Kuraymah that tied the navigable stretch of the Nile between the fourth and third cataracts into the transport system. Traffic in this case, however, was largely inbound to towns along the river, a situation that still prevailed in 1990.[2]