Over a week of violence in Yemen has left nearly fifty people dead, and many more wounded. The immediate cause was a 90 percent increase in gasoline (and other petroleum products) prices. The government had long subsidized fuel prices, but increases in the price of oil over the last year (caused largely by growing demand from China and other developing economies), has made the subsidized price about a third of what the government pays for oil. The resulting budget deficit was more than the government could afford. But there's more to it than that.

Oil was discovered in Yemen in 1986. Not a lot, at least by Persian Gulf standards, but billions of dollars worth. However, corruption has led to most of the oil wealth going to corrupt government officials, rather than the population as a whole. This was not a popular development. Moreover, Islamic conservatism has always been strong in parts of Yemen. Osama bin Laden's family came from Yemen two generations ago, and brought their Islamic conservatism with them to Saudi Arabia. The conservative tribes of Yemen are very pro-al Qaeda, and anti-Yemeni government. This has led to the Yemen government joining forces with the United States to fight against Islamic terrorism. This has not been a popular position to many Yemenis. It has been popular with Saudi Arabia, where, in the past week, the United States has issued two warnings to American citizens to be wary of attacks on them by Islamic terrorists. Some of the Islamic terrorism in Saudi Arabia is believed to come from supporters in Yemen.

This has added to the traditionally poor relations with Saudi Arabia. The Yemenis, for thousands of years, were much better off economically than the tribes in what is now Saudi Arabia. That's because most of  what little water that falls on Arabia, falls on Yemen. It was easier to grow food, and live, in Yemen. The ports of Yemen shared in the lucrative trade going on with India, Africa and Egypt. But all that changed when oil was discovered in Saudi Arabia. Now, the poor cousins were fabulously rich. With about the same population as Yemen, Saudis per capita income is over ten times that of Yemenis (where it's less than a thousand dollars a year). The Yemenis have not gotten over this disparity, and the Saudis are sensitive to the threat of "troublemakers" coming north from Yemen. Both countries accuse the other of supporting dissent and rebellion in each others population. There's some truth to this, but attempts to solve these problems diplomatically have not been completely successful. 

Yemen was never known for political stability. The tribal politics has always been vigorous, and nasty. The tribal loyalties are stronger inland, while the people in the coastal towns and cities are more open to new ideas. But overall, more violence is likely.