and are at loggerheads. They have long been rivals, but it’s all recently got a lot more tense. Here’s why.

How come and don’t get along?

and – two powerful neighbours – are locked in a fierce struggle for regional dominance.

The decades-old feud between them is exacerbated by religious differences. They each follow one of the two main sects in Islam – is largely Shia Muslim, while sees itself as the leading Sunni Muslim power.

Map showing Sunni distribution in Middle East
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This religious schism is reflected in the wider map of the Middle East, where other countries have Sunni or Shia majorities, some of whom look towards or for support or guidance.

Historically , a monarchy and home to the birthplace of Islam, saw itself as the leader of the Muslim world. However this was challenged in 1979 by the Islamic revolution in which created a new type of state in the region – a kind of theocracy – that had an explicit goal of exporting this model beyond its own borders.

Map showing Shia distribution in Middle East
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In the past 15 years in particular, the differences between and have been sharpened by a series of events.

The 2003 US-led invasion of Iraq overthrew Saddam Hussein, a Sunni Arab who had been a major ian adversary. This removed a crucial military counter-weight to ian influence in Iraq, which has been rising since then.

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Fast-forward to 2011 and uprisings across the caused political instability throughout the region. and exploited these upheavals to expand their influence, notably in Syria, Bahrain and Yemen, further heightening mutual suspicions.

’s critics say it is intent on establishing itself or its proxies across the region, and achieve control of a land corridor stretching from to the Mediterranean.

Read more: https://www-bbc-com.cdn.ampproject.org/c/s/www.bbc.com/news/amp/world-middle-east-42008809