The Red Devils made the trip to Thailand on Friday, four days before their opening friendly of the summer against English rivals Liverpool in Bangkok on July 12.
Man United will then head to Australia to take on Melbourne Victory, Crystal Palace and Aston Villa, before returning to Europe for their final two friendlies of the summer against Atletico Madrid and Rayo Vallecano.
Cristiano Ronaldo is absent from the party, as the Portugal international has been given time off by the club to deal with a personal issue.
There remains widespread speculation surrounding Ronaldo's future, with the attacker allegedly asking to leave the Red Devils this summer, but it is understood that his absence, both this week in training and in the tour squad, is down to a family matter rather than his future at club level.
Phil Jones is also absent, with Man United's official website revealing that the defender 'is following a specialist pre-season programme' due to his recent long-term knee injury.
Meanwhile, Brandon Williams, who is back at the club this summer following a loan spell at Norwich City, has missed out on the squad due to 'a small issue'.
Andreas Pereira is also not included, with the Brazilian, who has recently been on loan at Flamengo, believed to be closing in on a switch to Premier League newcomers Fulham.
Ethan Laird, Amad Diallo, James Garner, Hannibal Mejbri, Zidane Iqbal, Charlie Savage, Facundo Pellistri, Tahith Chong and Alejandro Garnacho have been included, though, and all nine players are likely to be given opportunities to impress at some stage of pre-season.
Tyrell Malacia has also been included following his recent switch from Feyenoord, with the defender becoming the first signing of the Ten Hag era at Old Trafford.
Elsewhere, Eric Bailly, Alex Telles, Axel Tuanzebe and Aaron Wan-Bissaka are in the selection despite suggestions that all four are available for transfer this summer.
Donny van de Beek is back at Old Trafford following a loan spell at Everton, and the Netherlands international will be determined to kickstart his Man United career under Ten Hag.
Man United's attacking options are limited due to Ronaldo's absence and the recent departures of Jesse Lingard, Edinson Cavani and Juan Mata on free transfers.
Ten Hag is allegedly considering giving Anthony Martial the chance to prove himself through the middle over pre-season, while Marcus Rashford could also be used centrally in the team's next few matches.
There are four goalkeepers in the squad, including Nathan Bishop and Matej Kovar, with both stoppers potentially leaving on loan before the end of the transfer window.
Jadon Sancho is also in the squad, and the England international will be looking to make his mark for the 20-time English champions this term following an underwhelming first season in the red of Man United.
Squad in full:
David De Gea, Tom Heaton, Nathan Bishop, Matej Kovar; Eric Bailly, Diogo Dalot, Ethan Laird, Victor Lindelof, Harry Maguire, Tyrell Malacia, Luke Shaw, Alex Telles, Axel Tuanzebe, Raphael Varane, Aaron Wan-Bissaka; Amad, Bruno Fernandes, Fred, James Garner, Hannibal Mejbri, Zidane Iqbal, Scott McTominay, Facundo Pellistri, Charlie Savage, Donny van de Beek; Tahith Chong, Anthony Elanga, Alejandro Garnacho, Anthony Martial, Marcus Rashford, Jadon Sancho