The division between Sunnis and Shias is almost as old as Islam itself – and although the two share many beliefs and practices, most members of either sect know little about each other. In the first of two editions of Heart and Soul for the BBC World Service, Shaimaa Khalil – herself a Sunni Muslim from Egypt – steps out of her religious comfort zone to explore the world of Shia Islam, and the roots of a division that all too often features in news reports about bloodshed in Pakistan and the Middle East.

Hardly a week goes by without news of sectarian bloodshed in Iraq – and in the civil war in Syria, President Assad, who belongs to a minority Shia sect, is pitted against majority-Sunni rebels. But are these really sectarian conflicts between the two main branches of Islam? And how have events in the Middle East affected Sunni-Shia relations elsewhere? In the second part of her Heart and Soul series, Shaimaa Khalil finds out – and discovers how much stronger sectarian identities have grown in recent years.