Australia veterans Adam Ashley-Cooper and Will Genia have both been included in the initial group of players selected by coach Vern Cotter for the Barbarians matches against England and Ulster.
The invitational Barbarians face England at Twickenham on May 28 before taking on Ulster in Belfast on June 1.
Wing Ashley-Cooper (116 caps) and scrum-half Genia (75 caps) were 2015 World Cup finalists when the Wallabies were beaten by champions New Zealand at Twickenham.
New Zealander Cotter, who is soon to be replaced as Scotland coach by Gregor Townsend, has also called up Argentina back-row Facundo Isa and Samoa prop Census Johnston who, in common with Ashley-Cooper and Genia, are now based with French clubs.
They will joined by New Zealand's Corey Flynn, with the veteran hooker now playing for Glasgow and uncapped Connacht centre Bundee Aki, who will become qualified for Ireland later this year through residency.
"The Barbarians is all about bringing together talented players from different countries and you can see from the first group of players selected that we've been able to do exactly that," said Cotter, who will leave Scotland to join French club Montpellier after the end of this season.
"We want to compete hard and to entertain in the best traditions of the club, so I'm looking forward to working towards that goal with all the players we'll have on board when we meet up next month."
The Barbarians will face England for the 16th time since 1990 next month, having won seven and lost eight in the overall series.
The Ulster match will be their first against the Irish province since 1957 but the Barbarians enjoyed a successful visit to Belfast last November, when they beat Fiji 40-7.
