In the second part of his series on the Sunni-Shia divide, Tarek Osman travels to the Middle East to examine the causes and forces behind the sectarian split today.

Conflicts raging in Iraq, Syria and Yemen all have a sectarian dimension with communities - who used to live side by side - now torn apart. Tarek follows history across the 20th century and the first decade of the 21st to understand how the Sunni-Shia divide has become so entrenched.

He wants to know if the current divisions echo the original split between the Sunni and Shia dating back 1400 years. Or whether sectarianism today is being used by powerful regional players to achieve their own geo-strategic and political goals.

In Lebanon, a barometer of sectarianism in the Middle east, he meets people from both Muslim sects to hear how religious identities are changing; and he visits a Syrian refugee camp to meet people who have been forced to flee their homes because of a war waged along sectarian lines.

Producer Neil McCarthy. Show less