The Islamic State was one state---The Khilafah State which insha'Allah is returning. It is a historical fact which no-one doubts that the Islamic world used to be one single state. It remained one single state since Allah (swt) honoured it with Islam until the arrival of the colonialists in the 18th Century; and since then turned into Feudal statelets fighting at border points, despite the fact that the Islamic world was all one single territory, and there were no borders except those adjacent to the disbelieving states, and even those borders were not permanent. There were only temporary borders waiting to be stormed while the necessary means were being prepared to continue the conquest of disbelieving countries and transform them into an Islamic homeland (Dar-al-Islam) ruled by Islam.
It is also a fact that at times in the past, the Islamic world turned into seemingly independent wilayahs, resembling little statelets, like the Ummayyad State in Al Andalous, or the Fatimide State in Egypt. However, despite that, the Islamic state remained one single entity and the Khilafah remained one; the authority that appointed the Wali and removed him, and never the Khilafah was at any time a federation of wilayahs, even at the height of Walis independence from the centre of the Khilafah, the state was always one, with one Khalif holding full authority in every single corner of the state, be it in the capital, wilayahs, towns and villages alike.
As for the events that took place in the Orient where the Walis enjoyed a relative independence, as in the case of the Seljuks, the Kamdanyyn, the Buwayhyyn and others, although they were independent in local administration, they were more like statelets rather than fully independent entities, and this state of affairs did not last long, for the Ottomans came and transferred the Khilafah to them, uniting in the process most of the Islamic homeland.
As for the Fatimide Khilafah in Egypt, this did not last long; for the Abbasside Khilafah worked hard at regaining Egypt and maintaining the unity of the Islamic lands, so the Fatimide Khilafah was abolished at the hands of the glorious commander ‘Salahuddine al-Ayyoubi’ and the unity of the Khilafah was reinstated, Egypt returned as an Islamic country under the Khilafah's rule.
As for the Ummayad Khilafah in Al Andalous, Abdul Rahman al-Dakhil broke away and did not give his Bay'ah to the Khalif, so the Khilafah state allowed him to have an independent administration. At the time, the international situation did not favour the Khilafah State's attempts at making Andalous a wilayah under its total control, but despite all this, Al-Andalous was never cut off from the body of the Islamic State, but had a separate administration. This allowed weakness to creep in and facilitated the disbelievers' bid in occupying it while the Khilafah State was at the height of its glory and might.
Therefore, all the attempts at dividing and dismembering the Islamic wilayahs from the Khilafah State or at establishing more than one Khilafah at a time were in vain; the Islamic State remained at all times one single entity until the colonialists arrived in the 18th century, since then the political onslaught aimed at dismembering the Islamic homeland began, and the attempts at abolishing the Khilafah gathered momentum, until this eventually happened in 1924.
Once the disbelieving colonialists had managed to destroy the Khilafah State, they occupied all the Islamic territories and ruled them directly; implanting in the process their concepts, thus they invented the concept of independence, not from colonialism but from the Islamic State; the disbelievers began motivating their agents from among the Muslims to proclaim the independence of each province from other provinces; as a result the Turkish state was founded, so was the Iraqi state, the Egyptian State, the Syrian State, and others. The disbelievers then went on to draw the borders of each state, and public opinion was concentrated in a way that prevented the possible unification of the Islamic countries, and the return of the Khilafah State.
The liberation of Muslim lands from all the legacies of the disbelieving colonialists is the duty of all Muslims, and the appointing of one Khilafah and the re-establishing of the Islamic Khilafah is also a duty on all Muslims, which if any Muslim neglected he would be sinful and rebellious, and deserving of Allah's punishment for not fulfilling their duty. Since the division of Muslim land was the filthiest act the disbelieving colonialists perpetuated in Muslim countries after abolishing the Khilafah, and since Islam makes it obligatory to abolish division and the imaginary political borders which the colonialists have drawn between Muslim countries, the establishing of a political party with Islam as its principle is indispensable.