South Sudan's rebel leader has arrived in the capital, to join a government of national unity and establish peace in the war-ravaged country.

Riek Machar, who is to be inaugurated as the country's vice president under his rival President Salva Kiir, arrived in Juba Tuesday afternoon.

Many observers hope Machar's return, which follows a peace deal signed with Kiir last year, will herald peace in the world's newest country after more than two years of civil war.

Tens of thousands of people have been killed in the conflict, which started in December 2013 when the security forces in Juba appeared to splinter along ethnic lines. Machar later fled the country and became the leader of a violent rebellion.