Kshtariya were the Royal class which constituted of Kings, Nobles and Military Officers. They were the rulers and their dharma/ duty was to protect and govern cities across India.
It used to be unthinkable for a Kshatriya to marry outside his class. It would be breaking the biggest tradition of his family and would cause disgrace to his whole family community. There is a very strong emphasis on following the customs and traditions of the class which have evolved over centuries. In addition to these, there are also further traditions which will be specific only to particular prominent Kshatryia families which has been handed down from generations. Following these traditions are a matter of great honour and importance that breaking them has resulted in families splitting up or being excluded permanently from the caste (jati). The Joint family system is still widely practised among the Kshatriya families and the family elders have the final say on all important decisions. The Kshatriyas were assigned to be protectors of Dharma (duty/justice) and their people.They were sanctioned by the Gods to serve humanity. The noble king is regarded as a Dharma Raja (Just Ruler). People ruled by aryas (honourable men) are led by the Divine light.
Kshtariya Dharma is specifically described in the Mahabharata: "Have you never heard the Kshatriya Dharma: Stand straight and never bow down, for this alone is manliness. Rather break at the knots than bend!" (Mahabharata, as retold by William Buck, University of California Press Berkeley Los Angeles London 1973)