To understand all of this, one has to understand first the map, and second the geography of Yemen. First of all, take a look at the Persian Gulf in a map. What you should note:
1) Of the states shown in the picture, there are 6 joined in a political and economic union (meant to someday strengthen all ties between the states involved). This is called the Gulf Cooperation Council (GCC), and it includes Saudi Arabia, Kuwait, Qatar, Oman, the United Arab Emirates (UAE), and Bahrain. Of them, some are richer and some are poorer. Some are more populous and some less. Yemen is not in the GCC, but was close to joining when all the turmoil began.
2) These GCC states cooperate openly and hugely to ensure that they all remain stable. For example, when the financial crisis hit world markets, Abu Dhabi had to bail out Dubai (both Emirates in the UAE) to the tune of $20 billion. This has not stopped within country borders: in 2011 when the Arab Spring started, the Gulf states went on high alert. So when Bahraini protesters began the mostly nonviolent Pearl Revolution, with hundreds of thousands taking to the streets, the GCC states sent the Peninsula Shield Force (composed of Saudi and UAE troops) to quell the protests. It should be noted that the Peninsula Shield Force was established to stop outside attacks, not meant to put down revolts or rebellions or protests.
To explain why these networks played out how they did, you have to understand first the oil reserves and riches of each country, and then the network each country is built on.
According to the Energy Information Administration, Saudi Arabia has the second largest proven oil reserves in the world, at 16% (behind Venezuela, who has 18% of the world’s oil). That’s right, nearly one-fifth of the world’s oil can be found in lil ol’ Saudi Arabia. They have a population of less than 30 million, allowing them to provide their citizens with great public sector jobs that make the country essentially full of public sector and family-based workers/businesses, without any planning for the future (attempts to do so have failed so far, but may work later). Saudi Arabia has squirreled away a nest egg estimated at $750 billion. This would be enough to fund the government for at least 2 years without selling a drop of oil. Even with lower oil prices, Saudi Arabia can weather deficits for decades without a serious cut to domestic spending by dipping into their reserves. They have reserves that are nearly double those of Russia, and only one-fourth of the population size to cater them to. Additionally, because their population is mostly Sunni, they have been able to blame any unrest and unhappiness on the Shi’a population and accuse Shi’a citizens of colluding with Iran (unlikely), while paying off their citizens to keep them compliant. Whether or not this will continue to work is up in the air, with as globalization increases the clamor for democracy. A looming succession crisis may provide the spark needed for a revolution, but their system has worked so far, unlike Yemen’s.
One of the other rich Gulf States, Kuwait is a bit of an interesting case. They have a quasi-democracy, with ineffectual institutions giving the impression of democracy. The country’s control is still vested in the Emir and the royal family. They have a small population of less than 4 million, and have the 6th largest proven oil reserves in the world (6% of world’s oil). These have proven a huge boon here as well. While their population is more diverse, with a 60-70% Sunni population and the rest Shi’a, they have largely managed to avoid sectarian tensions. They’re more willing to compromise and act, and money always helps.
Possibly the best off in terms of the Gulf States, Qatar is both thoroughly Sunni (as Saudi Arabia) and very small in population, while very wealthy. Their population is around 2 million, and they have very few problems: they emerged almost entirely unscathed in terms of open protest from the Arab Spring. Some chalk that up to their ability to use Al Jazeera to report on news elsewhere, while dealing with possible dissidents by promising to house them as long as they cause trouble for other regimes (i.e. Muslim Brotherhood). They’re also extraordinarily active on the world stage, they are guaranteed protection by the largest U.S. airbase in the Gulf (Al Udeid), and they have served as mediators in the past in Yemen, Lebanon, and Sudan, while maintaining ties with the Muslim Brotherhood, Hamas, and various other political Islam groups (groups that have Islamic values but seek to push them into politics). Qatar has the 13th largest proven oil reserves (2% of world’s oil), but they make up for it with an abundance of natural gas, having the third largest reserves of it in the world (12.6% of world’s natural gas).
United Arab Emirates
This one is a bit of a stranger case, because of the way the Emirates system works. Some of the regions are poorer than others (i.e. Sharjah), while some are centers of finance and wealth (i.e. Dubai). At any rate, the UAE has the 7th largest oil reserves (6% of the world’s oil), and a population of less than 10 million. Inside that population is also significant homogeneity, helping them avoid sectarian tensions: over 80% are Sunni rather than Shi’a Muslims, and they have diversified their income by building a financial hub in Dubai and Abu Dhabi.
This one is even weirder than the rest. Led by Qaboos bin Said al Said, one of the most beloved rulers of Oman (and who has been in power since the early 1970s), the country has weathered storms and economic troubles with relative ease. They have a population of less than 4 million, and though they are 24th in proven oil reserves (0.3% of world’s oil), the money is still flowing. Oman is close to a potential succession crisis, as their leader has been ill for quite some time, possibly terminally, and he has not designated a successor. If the family does not agree upon a successor to him within 3 days of his death, they’re supposed to open a letter that will (presumably) state his choice. However, the potential for lying, forgery, a loss of faith, and upheaval over his choice and letter is very large, and Oman’s dwindling oil reserves could prove a potential problem in the future for a state so dependent on these sources of income. Luckily they have avoided sectarian tensions, perhaps because Oman is composed mostly of Ibadi Muslims (a rare sect of Islam), making the country a bit unique on the typical “Sunni-Shi’a” axis we think about.
This is the biggest hotbed of trouble for the Gulf, and bears the most resemblance to Yemen. Bahrain has a population of less than 2 million, but its oil reserves are dwindling (0.007% of the world’s oil) and they have virtually no natural gas (0.04% of world’s natural gas). Most estimates put them at running out in 20 years tops, and their government has been tense for quite some time. The main reason once again comes down to sectarianism and money: the minority Sunni (30%) population rules the majority Shi’a (70%). The exploitation and unfair treatment of the Shi’a has often inspired them to rise up, even alongside other downtrodden Sunni Muslims. The royal family has survived only by requesting help, using ruthless force, and exploiting the Sunni-Shi’a divide to claim the Shi’a are trying to massacre the Sunni minority. They required bailouts and military assistance to put down the mostly nonviolent Pearl Revolution that sprang up in 2011, and they are still precariously perched on the brink of civil war.
Now we come to Yemen.
When we look at the factors that determined the stability of the above countries, we narrow it down to a few that I’ve described in each case:
1) Oil: Can the country pay its citizens off? The question here is overwhelmingly no, as far as Yemen goes. They have poor oil reserves for a population of 24 million (three-fifths of the oil Oman has, and nearly 7 times its population) and their production has declined since 2001. Their citizens are poor, and they have a catastrophic water problem on the horizon. Yemen is a poor economic wasteland at this point. Like Bahrain, it struggles to provide income for basic services that could buy off its citizens.
2) Sectarian Tensions: How does the country see itself? In the south is a hotbed of Al Qaeda affiliates, fighting for the Sunni cause. In the north came the Shiite Houthis, with reported Iranian support. The previous leader, who had kept it all together very tenuously with tribal alliances, was removed in the wake of the Arab Spring. The population is basically evenly split between Sunni and Shi’a, and sectarian tensions are and have been high. The Houthis have now taken over the country, but this will not likely stop the fighting: Al Qaeda is still active in the south. Like Bahrain, the Sunni-Shi’a divide has provided an evident backdrop to the fighting, though some (like Frederic M. Wehrey in Sectarian Politics in the Gulf) point out that sectarianism is fanned by structural inequalities and leaders use thereof, rather than being the cause of the conflict itself.
3) International Support: Can they get help? While the Sunni states around, particularly Saudi Arabia, were able to help the previous regime, they gave up a long time ago. Saudi Arabia now sees investment in Yemen as a waste of time. It’s said that Iran assists the Houthis, Al Qaeda continues to get support from radical Islamists in other states (like Saudi Arabia), and the President deposed during the Arab Spring in 2012 is accused of making a pact with the Houthis. So they don’t get help, and the central government was left to fend for itself as a result. Compared with Bahrain, the lack of international assistance may have made the difference: Bahrain stood a chance with intervention, but Yemen stood no chance without one.
Note: I included foreign workers in population counts. Not that it’s too big a deal, it’s meant for relative comparison. Foreign workers composing a population may cause trouble for the Gulf monarchies in the future, but I have excluded that from this article as they have yet to begin a conflict within any Gulf monarchy.