How the Islamic civilization emerged in the Balkan Peninsula is one of the most complex problems and requires multi-dimensional research. Unfortunately, many historic facts concerning Islam and the Balkan Peninsula have been "forgotten," or even distorted. This has been the result of centuries of pressure from the Serb and European historians and their political establishments.
The two ways that enabled the spread of Islam in the Balkans were:
(1) The military expeditions sent to extend the borders of the state of Islam, and
(2) The persuasive powers of the Islamic teachings themselves made people ultimately embrace it.
Insofar as the nations of the Balkan Peninsula are concerned, the overwhelming historic evidence reveals that military expeditions were of little significance in the spread of Islam. Thus, the teachings of Islam were the crucial factor in winning people over. The Quranic declaration that "there is no compulsion in religion," gave people the feeling of freedom for the first time in centuries. The very famous Albanian writer, S. Frashëri, observes: "Apart from the usage of military might to spread Islam, there does exist another way without turning to invasion or the force of arms, a way that is often not mentioned by the historians." Arnold Toynbee considers this a major point and mentions it in his book, too.
Looking back in history, it is easy to understand which way was the most influential means of spreading Islam; the force of arms or Islamic teachings. Most of the time, the Muslim armies only opened the "door" for the Islamic civilization to present itself, and ultimately the people would see the difference.
Islamic civilization entered the Balkan Peninsula mainly from the West through the contacts with Andalusia in Spain, from the South through Mediterranean Sea and Sicily, and from the Northeast through Hungary. Even though the evidence is minimal, after a serious analysis, the above question—how did Islam come to the Balkan Peninsula—would be finally answered.
After all the research, three are the ways through which the Islamic civilization gained its foothold in the Balkan Peninsula, and a further elaboration of them will follow.
Trade relations
The development of Islamic civilization and of the Muslims themselves conditioned the expansion of trade. The goods produced were mainly traded with neighboring nations, however, the traders often ventured even further to far and unknown places. This is why that since the 9th century trade relations between Europe and the Middle East through the Mediterranean Sea has been booming. In these trade relations, the most daring Europeans were those from Florence, Venice, Pizza, Genoa, followed by the French, and Catalonians. The European merchants through Egypt and Syria ventured far into the Far East.
The Illyro-Albanians had established trade relations with the Arab and Turkish nations, and not only the port-cities of the Adriatic Sea, but the rural parts of the Balkan Peninsula inhabited by them as well. Such strong trade relations had been established since ancient times, and continued into the pre-Ottoman and Ottoman periods.
The Arab gold and silver coins excavated in Potoci, near Mostar of the present-day Bosnia-Herzegovina, date back to the time of Marwaan II (744-750 C) which tells of the extensive trade relations the Muslims had with the Balkan nations, first the Albanians and later the Slavs.
Port-cities along the Adriatic Sea like Dubrovnik, Tivari, Ulqini, Durazzo, Valona, Himara, etc., and other Greek and Southern Italian cities were centers of trade. During the 12th century, the well known Muslim historians and travelers, Al-Idreesi and Ibn Hawkal, tell in fine details the social and political situation of those places. They also describe the road going through the Balkan Peninsula, from the Aegean Sea along the valley of the Vardar River to the coasts of the Adriatic Sea.
Usually, the Italian merchants traveled by sea, whereas the Muslims mostly traveled overland. The merchants from Venice and Florence used to trade regularly and exchanged their goods mostly in Istanbul and Gallata. Well known are also the caravans from Dubrovnik to Istanbul, and vice versa.
Such strong trade relations have had a great impact on the Balkan nations. Apart from buying and selling, which was the primary intention, the merchants brought many new ideas and changes. This was intensified further when the Muslim merchants started to establish themselves in some fortified and secured coastal cities. The first Muslim colonies appeared. Though they were very small in the beginning, they became larger, and even stronger.
Military and political relations
The first part of this article highlights the ways in which Islam was introduced in the Balkans, with the trade relations being the primary focus. In this part, other factors are highlighted, namely: military and political relations with Muslim countries.
By 634, the Muslims, in their attempt to spread Islam to every possible area, had started to attack the borders of the Byzantine Empire, and made the first attempt to conquer Constantinople (now Istanbul). Some years later, in 717-718, the Muslim army under the command of Maslamah 
surrounded Constantinople, however, they could not conquer it. In this expedition, the Muslim army penetrated as far as Adrianople (now Edirne) and Salonika, and this was known as the first contact by the Muslim armies with the Balkan nations. They also built a mosque near Gallata, known as the Arab Mosque. This ledsome Arabs (Muslims) to settle in Constantinople and Salonika.
In the 9th century, the Muslims were more direct in their intentions towards the Balkan Peninsula. This was simple to understand because they conquered Crete in 823, Sicily in 827, and some parts of the Southern Italy as well, and the Balkan Peninsula was next in line.
During 840-841, the Muslims conquered Taranto, Italy, and undertook incursions into the Balkan Peninsula, conquering Budva, Kotor, Rosi, and Rijeka. They even surrounded Dubrovnik for fifteen years, but without any success. This was the time when the Illyro-Albanians had their first contacts with the Muslim armies. They kept trying to take over the Balkan Peninsula until 1023 when they lost control of the Southern Italy.
The traces of this new civilization are to be found everywhere. Nearby the cathedral of Trogir, there is a statue of an Arab man wearing turban, which is a sign of well established relationships. There also are the tombs of two Arabs, which is evidence that they must have been living there for some time.
On the other hand, the conquest of Spain by the Muslims opened a new chapter in their relations with the Balkan nations. Some of the Slav tribes, especially the Slovenians and Croats, had good relations with the Muslim Spain. In the royal court of Haakimi I (791-822) there were 2000 guards of Croatian origin. Such a large number of guards indicated the extensive relations between them.
This variety of military relations was extended to the politics, too. The Muslim countries had cordial relationship with their Balkan counterparts. In 856, the Serb king, Mikhail III, sent his envoy to the Caliph Al-Mutawakkil Ibn Ar-Rasheed of the Abbasid dynasty to arrange a form of debate on religious matters.
In 922, moved by the Islamic teachings, the Bulgarian king sent an envoy to Caliph Al-Muqtadir of the Abbasid dynasty to convey his family’s decision to embrace Islam.
In this point, well known are the contacts that Caliph Haroon Ar-Rasheed had established with the European rulers. He had sent his envoy to the Serb king, Carl the Great, in order to establish cordial and reciprocal relations.
The Croat ruler, Prince Tomislav, had good relations with caliph Abdur-Rahmaan III and even used to exchange gifts. Abdur-Rahmaan III had sent envoys to all the Slav kingdoms to discuss and charter their future relations.
The Europeans, the Balkan nations included, kept continuous contacts with the Muslims—the Fatimids (969-1171), the Ayyubids (1171-1250) and the Mamluks (1250-1517)—because of various interests, trade being one of them.
The Slavs were allies to the Muslims against the Roman and Byzantine Empires. However, their relations with the Illyro-Albanians will define the future military and political actors of the Balkan Peninsula. At the beginning, those relations were cordial, but changed rapidly.
Yet, there were various contacts between the Muslims and the Illyro-Albanians. The fact that the Illyro-Albanians were ruled by the foreigners—the Roman and Byzantine Empires, the Serbs, etc.—means that they were almost never identified as an independent political entity.
Missionaries and migrations
Maybe the most important factor that influenced the rapid spread of Islam among the Illyro-Albanians was the work of missionaries and migrations of different groups of people. There are indications that travelers and theologian visited almost every part of the peninsula centuries before the Ottomans appeared and played an important role in preaching Islam. This was in some way assisted by the fact that the Muslims controlled many territories around the Balkan Peninsula (Southern Italy, some Greek islands, the Asia Minor, etc.), and by the incursions of the Muslim armies as well.
Maybe the most important among the migrations was a group of Turkish Muslims who settled in Southern Hungary (near the border with the Byzantine Empire) and somewhere near the Ohrid Lake (Macedonia) as well (almost in the center of the peninsula). This was the time when the first concentrated Muslim dwellings were seen in the peninsula.
The Russian Czar Theofil, while fighting in the Asia Minor, forced many Muslims to migrate. They settled in the Balkan Peninsula in the valley of the Vardar River. They came to be known the "Turks of Vardar."
Yet, the presence of the Muslims in the Balkan Peninsula was so great that the Christian kingdoms could no longer tolerate them. Thus, in the 13th century, many crusades directed to the Middle East passed through the peninsula and exterminated the Muslims living there.
