Syrian rebel forces led by Hayat Tahrir al-Sham, or HTS, declared they had ousted President Bashar al-Assad and he had fled Damascus on Sunday. But what is HTS, and how did it rock the long-simmering tensions in Syria? HTS is a Sunni Islamist militant and political group that traces its roots to the beginning of the Syrian civil war.

Standing before a cheering crowd in Damascus’ historic Umayyad Mosque, the broad and bearded Abu Mohammad al-Jolani declared a new chapter in Syria’s history.

The United States has asked Syria's Hayat Tahrir al-Sham (HTS) rebel group to help locate and free missing American journalist Austin Tice as it liberates the country's prisons in the aftermath of Bashar al-Assad's overthrow,

Leading the offensive and ending President Assad's reign is Abu Mohammed al-Julani, who currently heads the most powerful armed opposition force in Syria, Hayat Tahrir al-Sham (HTS), an Islamic group which once had ties to Al-Qaeda.

Sham, or HTS, that took over Syria and ousted President Bashar al-Assad, has yet to show how it plans to govern the country torn by more than a decade of civil war. CBS News contributor Sam Vinograd breaks down what's known about the opposition group in power.