From the end of XII century the Germans advance to the Baltic lands, where different tribes of the Baltic-Lithuanians (the Aiukshayts, the Zhemayts), the Latvians (the Latgals, Livs, Kurshes, Zemgals) and the Finno-Ugric (the Ests and Chud) lived. Russia tried to control these tribes and lay them under contribution. For these purpose Yaroslav the Wise ordered to found an outpost - Yuryev (Tartu).
Having conquered the coast-dwellering Slavs, the Germans invaded the Livs' territory (Livonia). In 1201 they founded Riga. By the year of 1224 all Estonia was conquered by the crusaders. German feudal lords destroyed local population and settled their own colonists on these lands. The people of Baltic and Russia joined against the Germans. The further progress of the Germans demanded association of forces and in 1237 the order of Sword-Bearers (or Livonian) became a branch of larger Teutonic Order.
In July, 1240 Swedish Fleet (under command of king's relative Earl Birgerom) followed the Neva and reached the Izhora Mouth intending to get to Novgorod trough the Ladoga. Warned by a friendly Izhora tribe leader Pelgusiy, Novgorod Prince Alexander (he was only 19 years old that time) steped forward with his armed force. The Neva Battle took place in July, 15, 1240. Surprise and agility determined to the benefit of the Novgorod people. It was a glorious victory. Later Prince Alexander was named Nevsky.
At the same time Russia was attacked by knights-crusaders. In 1240 they took Izborsk and Pskov and were in 40 km from Novgorod. The Novgorod Veche (city gemot) decided to return Prince Alexander who had been earlier expeled. Under command of Alexander the Russians freed the seized cities and moved towards the Order. The battle that occurred in April, 5, 1242 on a little thawed ice of the Chudskoye Lake was named 'Ledovoye Poboishe'. The triumph was due to military skill of Alexander Nevsky who took into account a number of circumstances of military and geographical character.
In 1206 at tribes gathering (Kurultai), which took place in the upper river of Onon, Temuchjin - the leader of Mongols was proclaimed the ruler of all Mongolian tribes. He was named Chingiz-Khan (it is usually translated as the Great Khan). Having created a strong and aggressive army, Chingiz-Khan began conquest.
Djebe and Subedei - military leaders of Chingiz-Khan's army found out a narrow flat passageway between the Caspian Sea and mountains near Derbent, their troops rushed into the steppes of the Polovtsy tribes. Having smashed the nomads, they began to move to Russian lands. Then one of Polovtsy khans - Kotyan asked Russian princes for help. Having such a dangerous enemy, Russian leaders could not refuse aid. The Mongols (overall strength up to 30 thousand) ensnared Russian army into steppe. And in May, 31, 1223 in the battle on the Kalka River they defeated Russian forces. Only one tenth of Russian troops managed to return. Despite of success, the Mongols reached only the Dnepr and unexpectedly turned back to steppes. So that was the result of the first Mongolian campaign against Russia.
After Chingiz-Khan died in 1227, his successor Ugedei continued aggressive campaigns. Having seized the Volga Bulgaria, by the autumn of 1237, the Mongols crossed the Volga and concentrated on the Voronezh River. It was extremely difficult to resist numerous, well trained and violent armies of the Mongols without political and military unity in Russia. And nevertheless, Russian lands, especially in the beginning, tried to organize a collective repulse. But joint forces of several princedoms were insufficient to oppose such a strong enemy.
The first Russian volost in the way of the Mongols was Ryazan. Khan Batyi demanded voluntary submission and tribute, but Ryazan Prince Yury Ingvarevich allied with Pronsk and Murom Princes refused. Having received no help from other lands, the Ryazans were left alone and in December, 21, 1237 Ryazan fell after a five-day defence. The city was plundered and burnt, and the inhabitants, even a princely family, were killed.
In January, 1238 the Mongols moved against the Vladimir-Suzdal Land. In a battle near Kolomna they defeated Vladimir forces and the remains of Ryazan's. Then they came up to Moscow. The city was taken only after five days. In February, 3, 1238 Batyi reached Vladimir and besieged it, simultaneously he sent troops to Suzdal. On the 7th of February, after many unsuccessful attempts to seize the city through Golden Gate, aggressors rushed into through breaches in the walls. Northeast Russia was ruined and devastated.
The way to Novgorod was open for conquerors. However Batyi acted unexpectedly: he turned his armies to the South at Ignach-Krest (not more than a hundred versts from Novgorod). The withdrawal was very impetuous. The Mongols divided into groups and went southward, covering all settlements on their way. It is necessary to mention strong resistance of inhabitants of a small town Kozelsk (led by a young Prince Vasily), who defended their town without any help for seven weeks. They made sorties, attacked the enemy, destroyed battering-rams.
Smolensk managed to fight off, but such important centres as Pereyaslavl-Yuzhny, Chernigov and others were ravaged. After that the Mongols returned back to steppes again. But in 1239 a new invasion followed. After the capture of Murom, the Mongols moved to Southern Russia and approached Kiev. City defence was organized by the Voevode Dmitry (Prince Mikhail Vsevolodovich fled). The city-dwellers self-denyingly defended Kiev for about three months, but forces were unequal. In December, 1240 Kiev was seized.