Image copyright Getty Images

This year's Eurovision has an extra layer of controversy - because it's being held in Israel.

Although the country's not in Europe, it's taken part in Eurovision for more than 45 years and has hosted it twice before because it's part of the European Broadcasting Union.

But there have been calls to boycott the event by critics of Israel's policies towards Palestinians in the occupied West Bank and Gaza.

The conflict between Israel and the Palestinians has gone on for decades, and the dispute over land is at its heart.

How did it start?

Image copyright Getty Images Image caption Bethlehem in the early 20th century

A 100-year-old issue

Britain took control of the area known as Palestine after the ruler of that part of the Middle East, the Ottoman Empire, was defeated in WW1.

The land was inhabited by a Jewish minority and Arab majority.

Tensions between the two peoples grew when the international community gave Britain the task of establishing a "national home" in Palestine for Jewish people.

For Jews, it was their ancestral home, but Palestinian Arabs also claimed the land and opposed the move.

Image copyright Getty Images Image caption A Haganah (Jewish Underground) fighter just before the start of the Israeli War of Independence 1948

Between the 1920s and 40s, the number of Jews arriving there grew, with many fleeing from persecution in Europe and seeking a homeland after the Holocaust of WWII.

Violence between Jews and Arabs, and against British rule, also grew.

In 1947, the UN voted for Palestine to be split into separate Jewish and Arab states, with Jerusalem becoming an international city.

That plan was accepted by Jewish leaders but rejected by the Arab side and never implemented.

Image copyright Getty Images Image caption The soldiers of allied Arab Legion forces fire on Jewish fighters of the Haganah, the Jewish Agency self-defence force in March 1948

The creation of Israel and the 'Catastrophe'

In 1948, unable to solve the problem, British rulers left and Jewish leaders declared the creation of the state of Israel.

Many Palestinians objected and a war followed. Troops from neighbouring Arab countries invaded.

Hundreds of thousands of Palestinians fled or were forced out of their homes in what they call Al Nakba, or the "Catastrophe".

By the time the fighting ended in a ceasefire the following year, Israel controlled most of the territory.

Jordan occupied land which became known as the West Bank, and Egypt occupied Gaza.

Jerusalem was divided between Israeli forces in the West, and Jordanian forces in the East.

Because there was never a peace agreement - each side blamed the other - there were more wars and fighting in the decades which followed.

The map today

In another war in 1967, Israel occupied East Jerusalem and the West Bank, as well as most of the Syrian Golan Heights, and Gaza and the Egyptian Sinai peninsula.

Most Palestinian refugees and their descendants live in Gaza and the West Bank, as well as in neighbouring Jordan, Syria and Lebanon.

Neither they nor their descendants have been allowed by Israel to return to their homes - Israel says this would overwhelm the country and threaten its existence as a Jewish state.

Image copyright Getty Images Image caption Israeli military commanders arrive in East Jerusalem, after Israeli forces seized East Jerusalem, during the Six Day War in 1967

Israel still occupies the West Bank, and although it pulled out of Gaza the UN still regards that piece of land as part of occupied territory.

Israel claims the whole of Jerusalem as its capital, while the Palestinians claim East Jerusalem as the capital of a future Palestinian state. Only the US recognises Israel's claim to the whole of the city.

In the past 50 years Israel has built settlements in these areas, where more than 600,000 Jews now live.

Palestinians say these are illegal under international law and are obstacles to peace, but Israel denies this.

What's happening now?

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Tensions are often high between Israel and Palestinians living in East Jerusalem, Gaza and the West Bank.

Gaza is ruled by a Palestinian militant group called Hamas, which has fought Israel many times. Israel and Egypt tightly control Gaza's borders to stop weapons getting to Hamas.

Palestinians in Gaza and the West Bank say they're suffering because of Israeli actions and restrictions. Israel say it is only acting to protect itself from Palestinian violence.

For the past year, there have been violent scenes on the Gaza-Israel border.

Palestinians have protested there weekly, wanting refugees to return to their former homes in what is now Israel.

Israel says the protests are used as a cover to attack it. Dozens of Palestinians have been killed by Israeli troops, who say they are acting in self-defence.

Image copyright Getty Images Image caption Tear gas is fired at protestors during clashes with Israeli forces near the border between the Gaza strip and Israel

What are the main problems?

There are a number of issues which Israel and the Palestinians cannot agree on.

These include what should happen to Palestinian refugees, whether Jewish settlements in the occupied West Bank should stay or be removed, whether the two sides should share Jerusalem, and - perhaps most tricky of all - whether a Palestinian state should be created alongside Israel.

Peace talks have been taking place on and off for more than 25 years, but so far have not solved the conflict.

What does the future hold?

Media playback is unsupported on your device Media caption Gaza: The bullets stop, the burials go on

In short, the situation isn't going to be sorted out any time soon.

A new peace plan is being prepared by the United States, which has described it as the "deal of the century".

No-one knows what's in it yet, but the US says it will probably reveal it in May or June 2019.

However, the Palestinians say the US favours Israel and they have said they will not accept any plan put forward by the US.

Israel has indicated that it will wait and see what the plan involves.

If the plan works, it will end one of the world's longest-running conflicts.

But if it fails, the fighting will go on.

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