Datang, like the Tang dynasty that inspired the name, exits with remarkable achievements. The Tang Dynasty introduced woodblock printing and many of the first manuscripts. The Tang poets remain admired after a millennium. Datang has played a crucial role in wireless since developing the TD-SCDMA standard before 2007*. That was extended to 4G TD-LTE, which is the basis in turn for much of mid-band 5G. In fact, when the technology was developed for wireless in the 3.5 GHz band, it was called TD-LTE.
Datang was so important in wireless standards that only three weeks ago Qualcomm signed a major agreement with them (below.) They have thousands of patents; it is probably impossible to build a 5G network without using Datang patents. (Huawei and ZTE also have primary patents on advanced wireless.)
Datang is still known for test and measurement equipment, but at $3B sales/year was too small to compete.