When you turn up to watch a show, it's all about what happens on stage. The months of rehearsal, the stage technicians beavering away behind the scenes, none of that matters in the moment.

But after the six special minutes of Kadamati have passed, and the young dancers are walking away triumphant, spare a thought for how the whole thing came about.

Choreographed by Akram Khan in 2016 for The Big Dance in Trafalgar Square, the piece has continued to have legs. This August, as part of the Edinburgh International Festival, it will be performed outside the Palace of Holyroodhouse by 300 young people drawn from dance companies and schools across the central belt.

'Something as simple as getting name badges for everyone or planning toilet breaks takes a really long time,' explains Jennifer Irons, mass movement director. 'And the reality of that dictates how much time you have to rehearse. So logistics kind of underpin everything and become an integral part of the creative process.'

Known for his incredible fusion of contemporary dance and Indian Kathak, Khan himself is performing at the International Festival in Xenos, his powerful solo about an Indian soldier fighting in WWI. For him, the chance to also stage a large-scale work with the local community is 'really exciting and beautiful' – but for the young people involved, it's an opportunity of epic proportions.

'We've shown them the piece being performed in Trafalgar Square, but the young people can't quite imagine how big this is, or how much detail and planning has gone into it,' says Katie Miller, one of the dance artists recruited to teach Kadamati to the groups. 'So we've let them know how massive this is and that things like this don't come around very often – it's definitely a once-in-a-lifetime experience.'

Xenos / credit: Jean Louis Fernandez

The youth groups were chosen as a tie-in with 2018's Year of Young People in Scotland, but when the piece is performed again in Paris this September, it will feature 700 community dancers of all ages drawn from each of the city's arrondissements – the whole ethos of Kadamati is about people coming together as one strong unit.

'The themes of the piece have to do with identity, travelling, hope,' explains Irons. 'And about being an individual within society, and working out how you can contribute to that society but still maintain your individuality. Also the idea that by bringing people together, you can somehow create something that you can't do on your own.'

Part of a commission from 14-18 NOW, a cultural programme set up to commemorate WWI, Kadamati isn't directly about war – more how to avoid one.

'The piece isn't necessarily influenced by WWI, it's more of a response to how the world is these days,' says Irons. 'The whole notion that we're better off on our own, that difference should be shut out and kept away – this piece is an antidote to that.'

When Miller and the eight other dance artists were sent out to teach Khan's choreography to the groups, they were armed with videos, tutorials and online resources to aid them. But one thing was clear, regardless of each young dancer's skill level, the goal was to foster a spirit of synchronised individuality, not create 300 clones.

'The idea behind the piece was never supposed to be hundreds of people looking exactly the same,' says Irons. 'It's hundreds of people sharing an expression through Akram's movement. Our approach has been about sharing the themes and the intentions of the piece – that's the important bit, not that each dancer looks like the person standing next to them.'

Xenos, Festival Theatre, 16–18 Aug, 8pm, £10--£35; Kadamati, Palace of Holyroodhouse, 22 Aug, 6.15pm, free.