Islam entered Europe from the eastern side. The Muslims attempted many times to conquer the city of Constantinople (today's Istanbul) since the caliphate of Mu`awiyyah Ibn Abû Sufyyân. They could not overcome such city because of its strong forts until it was finally conquered by The Muslim leader Muhammad al-Fâteh in 857 AH. – 1453 AC.
Despite the fact that Islam had its positive scientific, civil and moral effects on the continent of Europe, some Europeans had deep hatred for Islam. For example, such hatred showed in the acts of Serbian massacres in which they killed the Muslims of Bosnian and Herzegovina out of ethnic cleansing.
The Muslims of Europe are minorities that differ in size according to the country they live in. The majority of the Muslims of Europe came to Europe as immigrants from countries that were occupied by such European countries. Also, great numbers of Europeans converted to Islam, a matter that led to more understanding of the religion of Islam. The Muslims of Europe face a lot of problems such as their ignorance of the modern and old history of Europe as well as the lack of intellectual and mature leadership of the Muslim minorities that may help a Muslim immigrant and guide him to the right. Moreover, Such Muslims minorities suffer from the internal problems such as the ethnic and intellectual disagreements. They also suffer from intellectual and spiritual alienation. Therefore, there a dire need for Fiqh of Muslim minorities * that studies their lives and problems in order to produce easy fiqhî rules that is more fit and easy for Muslims who live abroad.
Some western countries such as Britain and Swiss positively acknowledge Islam, while other countries such as Italy refuse to acknowledge Islam as an official religion. Germans view Islam as a threat to their community and the prime minister of Holland calls for closing Islamic schools.
We note that the number of Muslims in Europe increases. Those Muslims are loyal to Islam. They have, in general, some several rights such as the freedom of practicing their worship acts, establishing Islamic institutions, and building mosques – despite the administrate problems they might face. However, Muslims do face some obstacles when it comes to practicing Islam under the umbrella of a secular industrial society that does not care about the religious and spiritual aspects.
The Islamic presence in Europe
Islam started to enter Europe from the eastern side through continuous attempts of conquering the city of Constantinople since the caliphate of Mu`awiyyah Ibn Abû Sufyyân (41-60 AH(.
As to the western side, the leader Tareq Ibn Ziyyad managed to conquer al-Andalus (Spain) in (91 AH – 710 AC.). Muslims passed through al-Andalus to conquer France. The Muslim armies passed Pyrenees mountains and directed towards north till they reached Poitiers, where the battle of Balât ash-Shuhadâ' (Battle of Court of the Martyrs – Battle of Tours) occurred in 114 AH. – 723 AC. This battle ended by the defeat of the Muslim army and the killing of many of its soldiers. This battle stopped the Islamic expansion in this side of Europe. 
The Aghlabids, rulers of Tunisia, managed to conquer the southern side of Europe, through conquering the island of Sardinia in 95 AH. – 810 AC., then they controlled the island of Crete. After that, Asad Ibn al-Furât led a Muslim fleet to conquer the island of Sicily, which was the key to the south of Europe, in 212 AH. – 827 AC. and he also conquered Palermo in 216 AH. – 831 AC.
Most of the Italian cities used to seek the help of the Muslims when fighting each other, the matter that made it easy for Muslims to control some Italian coastal cities. Moreover, Pope John VIII had to pay Jizyah for Muslims when they threatened of conquering Rome in 484 AH – 872 AC. The island of Sicily was the link of trade between East Africa and Europe. It was also a place of mutual gathering of the civilizations of both Muslims and Europeans. 
However, al-Andalus is most important place of this mutual interaction of civilizations of Muslims and Europeans. It was considered as source of enlightening in West Europe. Specifically, the city of Toledo – which was taken by Spain in 478 AH – 1085 AC – became the minaret of knowledge that was sought by learners from all over west and Central of Europe. This city remained, for four centuries, the firs cultural and religious center in al-Andalus (Spain).
As stated previously, Muslims tried to conquer the south east of Europe through conquering Constantinople since the 1st century. Constantinople was finally conquered at the hands of Muslim leader Muhammad al-Fâteh in 857 AH. – 1453 AC. This leader had met the praise of the Prophet. For the Prophet said: " Constantinople shall be opened by Muslims and what a good army that would be and what a good leader that would be!!" Muhammad al-Fâteh made this city a capital of his reign, and he named it "Islambul, the Home of Islam", such name which the city kept and was pronounced later to "Istanbul". This city remained the capital until the fall of the Othman Caliphate. 
The Othman Caliphate also was the one that opened the Central of Europe. The Othman army opened the area of the Balkans in 756 AH – 1355 AC. All cites of the Central Europe were conquered by The Othman army. For example, Belgian was opened in 774 AH – 1372, Serbia in 788 AH – 1386 AC, Bosnia and Herzegovina in 792 AH – 1389 AC, as well as Croatia, Albania, Belgrade, and Hungary. The Othman armies, under the leadership of Sultan Sulaymân al-Qanûnî reached to the walls of Vienna and besieged this city in 936 AH – 1529 AC, but failed to open it. There was another attempt in 1094 AH – 1683 AC, but again failed to open this city.
Most of these lands were at the hands of Muslims under the reign of the Othman Caliphate during its golden years, but they started gradually to get their sovereignty when the Othman Caliphate became weak. By the year 1337 AH. - 1918 AC., the Othman Caliphate kept none of these cities but Istanbul. These European cities that that remained under the Islamic reign for long time are now Muslim-majority countries such as Macedonia, Albania, Bosnia, Herzegovina, Montenegro, and big Muslim communities in Bulgaria and Romania. 
The spread of Islam in these countries was due to the good treatment that the people of these countries received from the Muslims. Justice prevailed so that a village poor man can be elevated to the highest and most powerful positions in the Othman empire. Such social equity and justice was not existent in the European communities that were contemporary to the Othman empire. Under the Muslim reign of these countries peace replaced conflict and disorder. Europe benefited from the precise order of the Turkish military as well as from the administrative systems. The followers of other religions such Christianity and Judaism received good treatment in the areas that were ruled by the Othman empire. The evidence on this is that those people kept their religions, languages, and cultures. On the contrary, the Spanish – after taking al-Andalus in 897 AH – 1492 AC – forced the Muslims there to leave to West Africa and al-Mashreq al-Arabi (Arab speaking countries). The minority of the Muslims who decided to stay suffered from fanaticism and prosecution under the reign of unfair Spanish rule. Finally this minority was forced to convert to Christianity under the pressure of Spanish Inquisition.
Balât ash-Shuhadaa': Prof. Shawqî Abû Khalîl, Dâr al-Fikr al-Mu`âser, Beirut 1998, pp. 31- 45.
Al-Muslimûn fî ûrûbâ (Muslims in Europe): Mustafâ Disûqî Kasbah, Al-Azhar Magazine, Zu al-Hijjah 1417, pp. 39 – 40.
Narrated by al-Hâkem in al-Mustadrek, No 8300. Al-Hâkem said: It is an authentic hadîth. It was also narrated by Ahmad, No 18977, At-Tabrânî No 1216, Al-Haythamî No 10384 and others.
Fath al-Qustantîniyyah: Prof. Shawqî Abû Khalîl, Dâr al-Fiker, Damascus, first print 2005, pp. 57- 76.
Al-Muslimûn fî ûrûbâ (Muslims in Europe): Mustafâ Disûqî Kasbah, Al-Azhar Magazine, Zu al-Hijjah 1417, pp. 45 – 47.