Lanzhou-Xining-Lhasa fiber-optic cable

From Wiki China org cn

On September 16, 1997, the key state communication project, the Lanzhou-Xining-Lhasa optical cable communication line, was completed 25 days ahead of schedule after two months of painstaking work by 20,000 soldiers from the Lanzhou and Chengdu military districts. The 2739-km-long cable runs through 23 counties and cities of Gansu, Qinghai and Tibet, crosses the Qaidam Basin, theKunlun Tanggula mountain ranges, and is on average 4000 meters above sea-level. It was the first fiber-optic link between Tibet and the outside world.