Mainly because we later formed a multi-ethnic unified state, these wars are classified as civil wars. In the case of Russia, the earliest Kievan Rus' was actually only a little bigger, but since the occupation of Kiev in 882, it has continued to expand. At that time, Russia had a large number of small states, and after 300 years of mergers and wars, Kievan Rus' became the most powerful principality in Russia.
Although in 1240 the Mongols destroyed Kievan Rus' and soon Ivan received the title of Grand Duke from the Mongols, established the Duchy of Moscow, and defeated the main forces of the Golden Horde in 1380. Subsequently, the Muscovite Principality began to expand continuously, first by conquering Novgorod in 1477 and then by the fall of the Golden Horde in 1480. Soon a series of principalities such as Tver, Pskov, Ryazan and many others were annexed. The territory was expanded to 2.8 million square kilometers. In 1552, the Tsar began a war against the remnants of the Golden Horde, the first of which was the Kazan Khanate.
Then, in 1556, the Astra Khanate was destroyed, and in 1558 the Crimean Khanate was defeated, and the Battle remained until the Complete Defeat of the Tatars in Crimea in 1783. Soon, the Russians crossed the Ural Mountains and defeated the Sibil Khanate, the Evenks, the Yakuts, the Buryats, the Kolyaks and the Chukchis, and finally marched into Kamchatka in 1699, completing control of the whole of Siberia.
Subsequently, a large number of immigrants from Belarus, Poland, Ukraine and Lithuania entered Siberia, and by 1852, the number of white people in Siberia had reached 2.1 million, while the indigenous population was less than 600,000. At the same time, Russian troops also began a war against the Caucasus region of Central Asia, eventually conquering almost the entire region.
But now this history belongs to the Russian Civil War, not to the war of aggression. To give another example, Germany has established 3 empires in history, the most famous of which is the German Third Reich, where Hitler invaded and occupied many countries from Poland, the Czech Republic, Norway, Sweden, all the way to France, Austria and other countries.
However, after several years of war, these places were lost and all the countries occupied by Germany were restored. Therefore, historically this is a war of aggression.
Some of the so-called very powerful empires that we think of, such as Rome, Alexander, the Ottoman Empire, and so on, are actually the case in Germany. Although for a period of time, the force was strong, but it soon declined, and eventually lost all the territory. It's just that now history seems to be more powerful, how to occupy many countries, in fact, how much to eat, and how much to lose, it is simply a waste of work.