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 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 stay for a night as part of the Cao Bang Loop. Otherwise, you would just pass it. Though locals are friendly, and as not many foreigners stay there, you will be approached a few times by locals who would like to practise their English. Oh, and you might get stared at – a lot.