What is dar ul harb?

Answer 1

Dar al-Harb (دار الحرب) literally means "House of War" and is an Islamic legal designation for those territories not under the control of Muslim authorities AND who have not entered into a treaty of submission or sublimation to a Muslim authority. At present, since no country is in a sublimatory treaty with the Muslim authorities, Dar al-Harb effectively becomes a term to refer to Non-Muslim Majority countries. (Those countries that are in treaty are called Dar al-3ahad.)

The reason that these lands were called "Dar al-Harb" was from the theocratic Islamic notion that those areas where Islam does not currently rule should eventually be compelled to come under Islamic Rule. If they do not submit willingly, then war and other forms of violence may be used. These days, fewer and fewer Muslims support the idea of war to compel others to submit to theocratic Islam.

Answer 2

country under foreign rule