On Wednesday, seven people were killed when a suicide bomber set off an explosion in a bus full of Israeli tourists at an airport in the Bulgarian coastal town of Burgas.

Investigations into the incident continue; the bomber himself died in the attack, as did the Bulgarian bus driver and five Israeli vacationers. Dozens more were injured. Israel has blamed Iran and its proxies, and the anti-Semitic attack has increased tensions between the Middle Eastern countries.

But why were these tourists visiting Bulgaria in the first place? As it turns out, the Eastern European country -- and especially the city of Burgas -- is a popular destination for Israeli travelers.

Taking Flight

Israelis looking to escape the hot, dry summers of their homeland can find respite in Bulgaria, which has mild summers and a generally temperate climate. Burgas sits right on the Black Sea; its Sunny Beach, which is hugged by a string of hotels and restaurants, has become a popular spot for international travelers. It was the intended destination of the bus that was bombed on Wednesday.

At first glance, Israel and Bulgaria seem to have little in common. They are nearly a thousand miles apart and have few readily apparent cultural commonalities. Israel is a majority-Jewish state where less than 2 percent of the people adhere to Orthodox Christianity, whereas most Bulgarians are Orthodox Christians and less than 2 percent of the population is Jewish.

It is interesting, then, that Bulgaria is home to the largest synagogue in southeastern Europe, a gorgeous structure in the very center of Sofia, the capital city.

And in Israel's capital of Jerusalem, you'll find a giant white church -- also in a central downtown area -- called the Holy Trinity Russian Orthodox Cathedral.

The fact is, these countries do have a strong cultural and historical association. The tourists who met their deaths Wednesday were in Bulgaria thanks to connections that predate the foundation of the state of Israel.

From Segregation to Salvation

Things did not begin auspiciously. Bulgaria was allied with Nazi Germany and the Axis powers during World War II; it was during this period that the government enacted a law to enforce discrimination against Jewish Bulgarians. Under the 1941 Law for Protection of the Nation, these citizens were no longer allowed to run for office, marry ethnic Bulgarians, own farms or even vote.

Then came a new piece of legislation in 1943, stating that Bulgaria would meet German demands to deport all of its nearly 50,000 Jews for resettlement in Poland (in reality the gas chambers of Auschwitz), as was happening in other countries allied with the Axis.

But dissenters within the government, led by parliamentary politician Dimitar Peshev, were able to resist the decree. Due largely to their efforts, Bulgaria did not engage in mass deportations. Though some Jews in neighboring Thrace and Macedonia -- territories promised to Bulgaria in exchange for its support of Germany -- were rounded up before news of the bill's cancellation could reach them, most of Bulgaria's Jews were able to remain safely in their own country.

After World War II was over and Bulgaria became a Communist state, tens of thousands of Jewish citizens migrated to the newly formed state of Israel. That forged a tie between the two countries that remains strong to this day, especially since Bulgaria is remembered as one of the few countries in Europe that stood up to protect its Jewish population.

Still, the relationship was not without hiccups. The two countries had a long falling-out following the Six-Day War of 1967, when Israel launched a surprise attack against Egypt and captured territories from Egypt, Syria and Jordan.

As an Eastern bloc state, Bulgaria followed the Soviet Union's lead in cutting off all diplomatic ties with Israel following the Six-Day War. But in May 1990, soon after the downfall of communism, after 23 years of silence, the two countries rekindled their old flame, established diplomatic relations again, and signed a new agreement for economic cooperation.

Visitation Rights

Recent years have seen efforts to ramp up trade and tourism between the two countries. Bulgaria has had a recent spike in the number of Israeli visitors, especially since neighboring Turkey, which used to attract about 800,000 Israeli visitors every year, according to the Bulgarian newspaper Novinite, has made a diplomatic pivot towards Arab countries in recent years.

The number of Israeli tourists in Bulgaria reached a new high of 138,613 last year, according to the Bulgarian Ministry of Tourism. The Bulgarians, keen to maintain those ties, worry that Wednesday's attack will frighten Israeli tourists away.

Bulgarian Foreign Minister Nikolay Mladenov said the incident was a horrible tragedy, according to the Times of Israel. But he added that this was the first time something like this has ever happened in Bulgaria.

I want to assure everybody that we are a friendly country, he said. This was a one-time event, and we want tourists to keep coming.