China - Vietnam train running between Nanning and Hanoi and China - Mongolia train between Beijing and Ulaanbaatar have been resumed recently, after being suspended for 5 years.

Beijing – Ulaanbaatar Train Stopping at Erlian Port

 

Soft Sleeper Cabin on Hohhot – Ulaanbaatar Train

Numbered K23/K24 as before the Covid-19, the pair of trains bring great conveniences to tourists although they run only once a week. Beijing sends K23 at 07:27 every Tuesday, which arrives in Ulaanbaatar at 14:35 on Wednesday, while the return train K24 departs from Ulaanbaatar every Thursday, running from 07:18 to 14:35 the next day. To complete this 1,553-kilometer (965-mile) journey, about 31- 31.5 hours will be taken. On Beijing to Ulaanbaatar trains, a soft berth costs CNY 1,854, while a hard sleeper requires CNY 1,291. If traveling back to Beijing from Ulaanbaatar, CNY 1,090 and CNY 960 are needed respectively.

Actually, cross-border trains between China’s Hohhot and Mongolia’s Ulaanbaatar, aka trains 4652/4653/33 and 34/4654/4651 have been resumed on March 15, 2024. However, at that time, passengers in Beijing had to take a high speed train to get to Hohhot first and then take the connecting train to Mongolia. These trains are still in service now, departing every Monday and Friday with a duration of 24.5 - 36.5 hours.
  Numbered as train T8701/T8702, they run overnight with the travel time of 12 - 12.5 hours. Every day, this pair of trains leave Nanning and Hanoi at 18:05 and 22:20 respectively and gets to the destination the next morning, specifically, at 06:30 and 10:06. Only soft sleepers are offered on the train, costing CNY 215/berth. Passengers planning to extend their trip to/from Beijing can take the connecting train Z6/Z5.

Nanning – Hanoi Train

  Different from traditional style K23/K24 and T8701/T8702, they are high speed trains. Actually, they are the first high speed trains connecting China and a neighboring country. Train D87 departs from Kunming, Yunnan Province in the morning and arrives in Vientiane, capital of Laos in the afternoon, meaning that people can travel between the two countries by train within one day. The opposite D88 serves passengers heading to Kunming from Vientiane with a duration of 9.5 hours.
  China - Russia Train K3/K4, undergoing trial operation from February 25 to March 11 in 2025, is expected to restart service soon. The exact date is not yet known, but it is highly likely to be within this year. The train will depart from Beijing, pass through Ulaanbaatar, the capital of Mongolia, and finally arrive in Moscow. Due to its 7,826-kilometer running distance, passengers will spend 6 days and 6 nights on this train travel. 

Train K19/K20 once also linked China and Russia, but it ran along another route: Beijing – Manzhouli – Moscow. It’s still in suspension, and there is no news about its resumption. The same is to Beijing – Pyongyang Train K27/K28, Urumqi – Almaty Train K9795/K9796 and Urumqi - Astana K9797/K9798.