Tra Linh is a small town in the north-east of Cao Bang province on road TL210, next to the Chinese border. This place clearly has a border town feel to it with the amount of lorries waiting here overnight to cross the border.
The only real reason to stop here is either for lunch, or to find a place to sleep when doing the Cao Bang Loop. Otherwise you would just pass it. People here are friendly, and as not many foreigners stay there, you will approached a few times by locals who would lie to practise their English. Oh, and you might get stared at – a lot.