He defeated the Khazarui, the most civilized of all those Oriental people, and once the most powerful.

He subjugated the Pechenegs, perhaps the most brutal and least civilized of all the barbarians.

But these were only incidental to his real purpose.
The Bulgarian Empire was large, and had played an important part in the past.

It had a Tsar, while Russia had only a Grand Prince, and, although now declining in strength, was a troublesome neighbor to the Greek Empire.

The oft-repeated mistake of inviting the aid of another people was committed.