Abu Dhabi has a diverse and multicultural society. The city's cultural imprint as a small, ethnically homogeneous pearling community was changed with the arrival of other ethnic groups and nationals—first by the Iranians in the early 1900s, and later by various Asian and European ethnicities in the 1950s and 1960s. Abu Dhabi has been criticised for perpetuating a class-based society, where migrant workers are in the lower classes, and suffer abuse which "is endemic to the system". Major holidays in Abu Dhabi include ''Eid al Fitr'', which marks the end of ''Ramadan'', Eid ul-Adha which marks the end of Hajj, and National Day (2 December), which marks the formation of the United Arab Emirates.