Did the khilafah (caliphate) finish after the first four khulafah rashida?

No it did not. It continued until 1924 in the heartlands of Islam. We first need to distinguish between the the Khilafah (caliphate) system and righteous Khalifs - something that is often conflated. The khilafah is a ruling system, structural in nature ordained to implement the Islamic sharia. In it the caliph is at the apex, and underneath him a structure comprising assistants, governors, judges, commanders and administrators. Khalifs can be good, bad, mediocre and so on - the first four, some include Hasan as the fifth, along with other notaries in history as particularly pious. Others have been less so and some have been quite objectionable. However a good or bad caliph does not mean the system itself was unIslamic - just as a good or bad president in and of itself does not change a system from being a democratic one to a communist or socialist one. It is possible to show the continuity of the Khilafah system, from the time of the prophet upto 1924 to have been Islamic in nature, Islam being the core social force in determining its structure, laws and policies. This is demontrated by considering the historical reality and by the divine texts. Historically the core structure was based on the pillars mentioned above. - the Khalifah, who is head of state, - the Khalifah's delegated and executive assistants, - the commander of Jihad, - the regional governors, - the judiciary, - the advisory assembly representing the ummah (majlis al-ummah), and - the administrative apparatus. Throughout Muslim history, the above structure along with Islamic legislation were in place for the Khulafah Rashida, Umayyad, Abbasid and Ottoman caliphates. Successive historic reports (tawatur) cite judges resolving disputes from the prophetic era until the demise of the Ottoman caliphate in Istanbul with the shari’ah. The courts that settled infringement of rights, family matters, inheritance, criminal prosecutions, civil disputes and so on were always resolved in accordance to the shari’ah. There are no reports that any cases were resolved by any other legal system. The court records preserved in cities like Baghdad, Damascus, Jerusalem, Cairo, or Istanbul evidence this. Even laws that enacted in the 19th century to reform, standardise and unify the legal system were issued as rules permitted by Islam, with fatawa to allow them by the Sheikh al-Islam. The Shafi'i jurist Aamidi states:< br> 'And his (saw) saying 'After me the Khilafah will be for thirty years and then it will turn into a mulkan adoodan' this hadith does not indicate that the Khilafah is restricted to the Khulafaa Rashideen (they are Abu Bakr, Umar, Uthman and Ali (ra)) since their Khilafah lasted for thirty years as stated by the Prophet (saw). And nor does the hadith mean that there is no Khilafah after the Khulafaa Rashideen. Rather what is meant is: The Khilafah after me in terms of the responsibilities of the Imama and following my Sunnah without increase or neglect will be for thirty years, contrary to the period after this, when most of the ruling will be of muluk. Despite this, the continuity of the Khilafah is indicated by the following: The first: The Ijma of the Ummah in every age on the obligation to follow an Imam of that time and the fact the Imam and Khalifah must be obeyed. The second: He (saw) said: 'then it will become (taseeru) mulkan (hereditary rule)'. The personal pronoun (dameer) in 'taseeru mulkan' refers to the Khilafah. Since the mentioned verb cannot refer to anything other than the Khilafah, as if it is saying 'and then the Khilafah becomes a mulk (hereditary rule)' judging the Khilafah will become a mulk, the judgment on a thing requires the thing itself exists.'al-Imama Min Abkar al-Afkar Fi Usul al-Din (p.306) He argues the Ummah has a consensus on the first point due to divine texts ordaining the Imam of an age must be followed - it is not tenable to argue the hadith restricts any Khilafah after it. The second argument is linguistic, whereby a characteristic of the Khilafah will change but nothing so significant that the entire Khilafah will become something else. It is like saying 'Abdullah became angry'. This means there wa a change in his sentiment or temperament - and not the he became another person or animal. Likewise when the hadith comments, 'thumma taseeru mulkan', and then it became a hereditary rule, this does not mean it is no longer a Khilafah, something scholars of every era confirmed by accepting the caliphs and structures of governance, but an aspect has changed, a shift from a focus prophethood bought, from divine to temporal. The obligation of Khilafah or Imamah has always been is a pillar of Ahl al-Sunnah and even the Shi'a (who simply differ on whether the caliph should be from ahl al-bayt). It is why the Shafi'i jurist Taftazani wrote as his sharh of the Aqeeda of the Hanafi jurist Imam Nasafi: 'The position of agreement is it is obligatory to appoint an Imam. The difference of opinion is on the question whether the appointment must be by Allah or by His creatures and whether the basis [for appointment] is text or reason. The correct position is that the creatures must appoint a Khalifah because of the statement of the Prophet (saw), 'Whosoever dies without knowing the Imam of his time, dies the death of Jahiliyya.' He goes on to say: 'The Muslims must have an Imam, who will carry out the administration of their decisions, the maintaining of their restrictive ordinances, the guarding of their frontiers, the equipping of their armies, the receiving of their alms, the subjugation of those who get the upper hand and robbers and highwaymen, the performance of worship on Fridays and the Festivals, the settlement of disputes which take place amongst creatures, the receiving of evidence based on legal rights, the giving in marriage of young men and maidens who have no guardians and the division of the booty and things like these which individuals of the people are not entrusted.' [Sharh 'Aqeedat an-Nasafiyyah, p.147] Taftazani's comments are agreed upon by the Ahl al-Sunnah.