India
The Indus civilization in Sindh, Balochistān, and the Punjab probably flourished in the period 3250–2750 BC. Excavations indicate that the cities of this civilization paved their major streets with burned bricks cemented with bitumen. Great attention was devoted to drainage. The houses had drainpipes that carried the water to a street drain in the centre of the street, two to four feet deep and covered with slabs or bricks.
Evidence from archaeological and historical sources indicates that by AD 75 several methods of road construction were known in India. These included the brick pavement, the stone slab pavement, a kind of concrete as a foundation course or as an actual road surface, and the principles of grouting (filling crevices) with gypsum, lime, or bituminous mortar. Street paving seems to have been common in the towns in India at the beginning of the Common Era, and the principles of drainage were well known. The crowning of the roadway and the use of ditches and gutters were common in the towns. Northern and western India in the period 300 to 150 BC had a network of well-built roads. The rulers of the Mauryan empire (4th century BC), which stretched from the Indus River to the Brahmaputra River and from the Himalayas to the Vindhya Range, generally recognized that the unity of a great empire depended on the quality of its roads. The Great Royal Road of the Mauryans began at the Himalayan border, ran through Taxila (near modern Rāwalpindi, Pakistan), crossed the five streams of the Punjab, proceeded by way of Jumna to Prayag (now Allahābād, India), and continued to the mouth of the Ganges River. A “Ministry of Public Works” was responsible for construction, marking, and maintenance of the roads and rest houses and for the smooth running of ferries.
China’s Imperial Highway
China had a road system that paralleled the Persian Royal Road and the Roman road network in time and purpose. Its major development began under Emperor Shihuangdi about 220 BC. Many of the roads were wide, surfaced with stone, and lined with trees; steep mountains were traversed by stone-paved stairways with broad treads and low steps. By AD 700 the network had grown to some 25,000 miles (about 40,000 kilometres). Traces of a key route near Xi’an are still visible.
The Silk Road
The trade route from China to Asia Minor and India, known as the Silk Road, had been in existence for 1,400 years at the time of Marco Polo’s travels (c. AD 1270–90). It came into partial existence about 300 BC, when it was used to bring jade from Khotan (modern Hotan, China) to China. By 200 BC it was linked to the West, and by 100 BC it was carrying active trade between the two civilizations. At its zenith in AD 200 this road and its western connections over the Roman system constituted the longest road on Earth. In Asia the road passed through Samarkand to the region of Fergana, where, near the city of Osh, a stone tower marked the symbolic watershed between East and West. From Fergana the road traversed the valley between the Tien Shan and Kunlun Mountains through Kashgar, where it divided and skirted both sides of the Takla Makan Desert to join again at Yuanquan. The road then wound eastward to Jiayuguan (Suzhou), where it passed through the westernmost gateway (the Jade Gate, or Yumen) of the Great Wall of China. It then went southeast on the Imperial Highway to Xi’an and eastward to Shanghai on the Pacific Ocean. From Kashgar, trade routes to the south passed over the mountains to the great trading centre of Bactria and to northern Kashmir.
