During a visit last summer where he strolled through the tropical gardens next to Indonesia’s summer Presidential Palace, Abu Dhabi’s crown prince offered to build a grand mosque for his host, Joko "Jokowi" Widodo. If that seemed like a generous gesture, the two men struck a bigger bargain within months, appointing the de-facto ruler of the United Arab Emirates to chair the steering committee for a new $34 billion Indonesian capital city.

It was a strategic match. Jokowi, as the Indonesian president is known, is eager to find investors in an ambitious $400 billion infrastructure program. Sheikh Mohammed bin Zayed Al Nayhan is looking to expand his country’s presence in fast-growing Asian markets. But there’s more to it than that.

Since meeting during Jokowi’s Middle East tour five years ago, the two leaders have become firm friends, forging one of those rare personal relationships among world premiers that extend beyond economic cooperation and can redraw the map of political alliances. As Jokowi’s investment minister Luhut Pandjaitan put it, the two leaders have come to refer to one another as "brothers.”