What is Dar al-Kufr (the abode of disbelief), and what is the ruling concerning its inhabitants; are they Muslims, disbelievers, or polytheists?

Dar al-Kufr (the land of disbelief) is a land where the rulings of disbelief are enforced, and where Muslims do not have power and prominence. A Muslim or a disbeliever may live in this land. The mere residence of a Muslim in it does not necessitate his disbelief, but he may be obligated or recommended to emigrate from it, depending on his ability to perform the rituals of his religion.