Born in present-day South Sudan, Nyang Chiengjiek escaped the Sudanese Civil War some years after his father died in the conflict in 1999.
He was supported by the UN High Commissioner for Refugees at first, then began training with the Tegla Loroupe Peace Foundation in 2013.
That led to him being named in the inaugural Refugee Olympic Team Rio 2016, where he finished eighth in his 400m heat in a time of 52.89 seconds.
Now, he is ready for a second shot at the Games.
Started running in Kakuma
Nyang Chiengjiek took care of cattle as a young boy in South Sudan, but fled to avoid being recruited for the war as a child soldier.
He arrived in the Kakuma Refugee Camp in Kenya, where he went to school and started running, having joined some older boys who were training for long-distance events.
Speaking to the UNHCR in 2016, Nyang Chiengjiek explained: "That's when I realised I could make it as a runner – and if God gives you a talent, you have to use it."
However, there were teething issues at the start.
"All of us got a lot of injuries because of the wrong shoes we had," he said. "Then we were sharing. If maybe you have two pairs of shoes, then you help the one that has none."
He was eventually persuaded to try out for the Tegla Loroupe Peace Foundation, and he made the cut.
"Doing something good"
After racing at Rio 2016, the 29-year-old has gone on to represent World Athletics' Athlete Refugee Team (ART) as well.
In 2019, he was part of the ART at the IAAF World Relays, finishing seventh in the mixed 2x2x400m relay event.
Speaking back in 2016, Nyang Chiengjiek said of representing refugees: "By running well, I am doing something good to help others – especially refugees.
"Maybe among them are athletes with talent, but who did not yet get any opportunities.
"We have to look back and see where our brothers and sisters are, so if one of them also has talent, we can bring them to train with us and also make their lives better."
If selected for Tokyo 2020, Nyang Chiengjiek will have another opportunity to further the cause.