They are known as bidoon - or 'without' in Arabic - and by some estimates make up as much as 10 percent of Kuwait's population.
This weekend saw hundreds of Kuwait's bidoon, those Arabs whose ancestors migrated to Kuwait before its independence in 1961, protest against the oil-rich state's decades-long refusal to grant them citizenship. Riot police responded by firing tear gas and beating protestors with batons.
Roughly 105,000 bidoon live in Kuwait without full rights but are not recognized as nationals by any other state. Kuwait's interior minister blamed the unrest on people "outside Kuwait," according to AFP. That line certainly isn't new to the "Arab Spring." (See here, here, and here)
More from GlobalPost: Cast aside in Kuwait
The Open Society Initiative has a good, concise overview of the bidoon for further reading.