Thank you, dear questioner, for your interesting question about Islam.

In fact, this assumption is possibly based on the fact that Prophet Muhammad (peace be upon him) was an Arab, that most of the first generation of Muslims were Arabs, and that the Quran is in the Arabic language.

However, I want to let you know that Islam is meant for all people regardless of race, nationality, cultural or religious background.

From the commencement of the Prophet’s mission, the followers of Islam came from a wide range of lands and races. Among them was the Africans, the Byzantines, the Persians and the Jews.

All were united in the bond of Islam. In modern times, only about 18 percent of Muslims in the world today are Arabs.

The largest Muslim populations are found in Indonesia, the Indian sub-continent and other parts of Asia.

Islam is also widespread in many parts of Africa, and there are substantial minorities in Europe, north and south America, and Oceania. Islam is spreading in all continents including both Arabs and non-Arabs.

While "Arab" is a geographic and cultural term, "Muslim" refers to an adherent to the religion of Islam.

The Quran disclosed that Islam is indeed a global religion. Almighty God says,

And we have not sent you (O Muhammad) but as a mercy to [all] the worlds. (Al-Anbiya’ 21:107)

The Prophet (peace be upon him) naturally began the propagation of God's message among his own people, the Arabs, but that does not mean it was restricted to them.

Rather, he (peace be upon him) initially conveyed the message to those nearest him as a logical first step toward the realization of a long-term goal, namely conveying Islam to the whole world.

Later in his mission when conditions became more favorable, the Prophet (peace be upon him) sent letters of invitation to Islam to the rulers of the Byzantine and Persian empires, Abyssinia, Egypt, Damascus, Bahrain, Yamamah, Oman and others who represented the influential world figures of the day.

Whatever, their response to it, the Prophet's message was fully acknowledged by the major powers of his time. We hope this answers your question.

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Source: This answer is based on the book of Clear Your Doubts about Islam by Sahih International.