That is the rule: what counts in Islam is not race or color, but only piety. The Messenger of Allaah, sallallaahu ‘alayhi wa salam, divided the people into two types, depending on piety. It was narrated on the authority of ‘Abdullaah ibn ‘Umar, May Allaah be pleased with him, that he said that the Messenger of Allaah, sallallaahu ‘alayhi wa salam, said: "To go further: O people! No doubt, Allaah Has removed from you arrogance and pride; the characteristic of the pre-Islamic days of Jaahiliyyah. O people! The people are but two (types of) men: a pious believer who is honored in the Sight of Allaah, and a wretched disbeliever who is despicable in the Sight of Allaah." Then, he recited the following Statement of Allaah The Almighty (which means): {O mankind, indeed We Have Created you from male and female.} [Quran 49:13] [Ahmad, At-Tirmithi, Abu Daawood, Ibn Khuzaymah and Ibn Hibbaan]

The true Muslim is the one who goes forth to help anyone sharing him the same belief, no matter how different he may be in race, color and ancestry.
Thus, what counts in Islam is only belief and piety.
The Tatarian invasion in the period between 634-639 A.H.

After the five years that he spent (to establish himself in power) in both territories of Azerbaijan and Persia, in 634 A.H., Chormagan went around the Caspian Sea from the west and headed north to continue his invasions. He quickly controlled Armenia, Georgia (the Christian Kurg Kingdom), Chechnya and Dagestan. In the same year, another Tatarian army under the leadership of Batu Jochi started a new round of invasions in another direction; they went north of the Caspian Sea and suppressed the Turkish tribes around the Volga River. From there, in 635 A.H., they advanced towards the vast Russian territories. The horrible Tatar army launched a wave of atrocious massacres against the people of Christian Russia. Between 635 and 636 A.H., the army occupied all Russian cities, one after the other, beginning from Ryazan, then Kolomna, a few days later, then the huge city of Vladimir, after six days of resistance, in which a horrifying massacre was committed, after which the city of Suzdal was occupied. Then the Tatar army rushed towards the largest Russian city of Moscow, which was overrun and entirely ruined. Then, they occupied the cities of Yuryev, Golitsyno, Pereslavl, Rostov, Yaroslavl, and Torzhok. In this way, the Tatars occupied Russia entirely, even though it was as vast as seventeen million sq. m, having a huge number of people and harsh weather, and this was done in only two years (635-636 A.H.).

In the year 638 A.H., and under the leadership of Pato Batu Jochi, the Tatar army moved westward and occupied the Ukraine, 600,000 sq. m and overran the capitol Kiev, destroying its great treasures and killing most of its residents.
In 639 A.H., a division from the Tatar army under the leadership of Baidar advanced North-Westward of Ukraine and attacked the kingdom of Poland, and ruined many Polish cities. The Polish King had no way but to seek the aid of German cavalry, his neighbors, as Germany lies to the West of Poland. The German ruler, Henry, Duke of the German Silesia, came and with the Polish king, formed one army to face the Tatars, but it was bitterly defeated and Poland was occupied and controlled by the Tatars.

In the same year, 639 A.H., the Tatarian leader, Baidar, who was camping in the Ukraine, left a Tatarian division there and moved with the main army westward to Hungary where he faced the Hungarian king in a ferocious battle, and the whole army of Hungary was ruined and the country was occupied.
On his way from Poland southward to meet the other Tatarian army led by Bato, Baidar overran Slovakia and joined all of it to the Tatarian state. Then, the Tatarian armies advanced to invade Croatia. The Tatarian forces thus arrived at the coast of the Adriatic Sea, separating Croatia and Italy. This means that the Tatars managed to occupy nearly half the continent of Europe, and they could have gone even farther, given that the borders of the Tatarian state were drawing near Germany, Italy and Austria, except that their Khagan, Ogedei, had died in that year, 639 A.H. So Pato Batu Jochi left, appointing one of his commanders as his successor to be in charge of the conquered territories, as he had to return to Karakorum, the Mongolian capital, to contribute in electing a new Tatarian Khagan.

http://97.105.52.213/en/artical/20755/established-rule