Because terminology is helpful, we should mention two concepts that are dear to Muslims and which contribute a sense of unity, although in different ways.
First is the ummah, or the Islamic community, which has a local, immediate meaning but also extends to the entire membership of the Islamic faith, no matter where any one member finds themselves. This is similar to the idea of Christian fellowship that gives a sense of kinship to two individuals allowing them to connect on the street even if they’ve never met before.
Second is the notion of the dar al-islam, which is the ‘Abode of Islam’. This term is more concrete and refers to the actual geographical domain of the Islamic world. All Muslims yearn for great unity within the Abode of Islam, and in this way they are one with the heart of the Prophet who dedicated his life to unifying the tribes of Arabia. This second term can therefore have a more political meaning since it implies a political unity between groups.
Both of these concepts are central to the Muslim identity and it is part of the straight path to nurture within them.