In order to give a rough gauge,
Mongol Empire
1162: Genghis Khan born to a minor tribal chief (equivalent to maybe a landed knight?)
1174: Father is poisoned, tribe abandons him and his mother along with 4 brothers and a sister to the wolves. He is 12 then.
1175: After discovering his 2 half-brothers Bekhter and Belgutai were not sharing their spoils of hunting, rallied his other 2 brothers to confront them. Bekhter was killed and Belgutai remained loyal to Genghis for his life.
1182: Low point of Genghis, he was captured by his former allies. Convinced his guard to free him. Later the guards son becomes one of Genghis greatest generals. He is 20, and has no tribe or army to speak of still.
For the next part I will just cut and paste verbatim from wikipedia
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The Central Asian plateau (north of China) around the time of Temüjin was divided into several tribes or confederations, among them Naimans, Merkits, Uyghurs, Tatars, Mongols, Keraits that were all prominent in their own right and often unfriendly toward each other as evidenced by random raids, revenges, and plundering.
Temüjin began his slow ascent to power by offering himself as an ally (or, according to others sources, a vassal) to his father's anda (sworn brother or blood brother) Toghrul, who was Khan of the Kerait, and is better known by the Chinese title Ong Khan (or "Wang Khan"), which the Jin Empire granted him in 1197. This relationship was first reinforced when Börte was captured by the Merkits; it was to Toghrul that Temüjin turned for support. In response, Toghrul offered his vassal 20,000 of his Kerait warriors and suggested that he also involve his childhood friend Jamuka, who had himself become Khan (ruler) of his own tribe, the Jadaran.[9] Although the campaign was successful and led to the recapture of Börte and utter defeat of the Merkits, it also paved the way for the split between the childhood friends, Temüjin and Jamuka.
The main opponents of the Mongol confederation (traditionally the "Mongols") circa 1200 were the Naimans to the west, the Merkits to the north, Tanguts to the south, the Jin and Tatars to the east. By 1190, Temüjin, his followers and advisors united the smaller Mongol confederation only. As an incentive for absolute obedience and following his rule of law, the Yassa code, Temüjin promised civilians and soldiers a wealth from future possible war spoils.
Toghrul's (Wang Khan) son Senggum was jealous of Temüjin's growing power, and his affinity with his father. He allegedly planned to assassinate Temüjin. Toghrul, though allegedly saved on multiple occasions by Temüjin, gave in to his son[10] and became uncooperative with Temüjin. Temüjin learned of Senggum's intentions and eventually defeated him and his loyalists. One of the later ruptures between Toghrul and Temüjin was Toghrul's refusal to give his daughter in marriage to Jochi, the eldest son of Temüjin, a sign of disrespect in the Mongolian culture. This act led to the split between both factions, and was a prelude to war. Toghrul allied himself with Jamuka, who already opposed Temüjin's forces; however the internal dispute between Toghrul and Jamuka, plus the desertion of a number of their allies to Temüjin, led to Toghrul's defeat. Jamuka escaped during the conflict. This defeat was a catalyst for the fall and eventual dissemination of the Kerait tribe.
The next direct threat to Temüjin was the Naimans (Naiman Mongols), with whom Jamuka and his followers took refuge. The Naimans did not surrender, although enough sectors again voluntarily sided with Temüjin. In 1201, a kurultai elected Jamuka as Gur Khan, universal ruler, a title used by the rulers of the Kara-Khitan Khanate. Jamuka's assumption of this title was the final breach with Temüjin, and Jamuka formed a coalition of tribes to oppose him. Before the conflict, however, several generals abandoned Jamuka, including Subutai, Jelme's well-known younger brother. After several battles, Jamuka was finally turned over to Temüjin by his own men in 1206.
According to the Secret History, Temüjin again offered his friendship to Jamuka, asking him to return to his side. Temüjin had killed the men who betrayed Jamuka, stating that he did not want disloyal men in his army. Jamuka refused the offer of friendship and reunion, saying that there can only be one Sun in the sky, and he asked for a noble death. The custom is to die without spilling blood, which is granted by breaking the back. Jamuka requested this form of death, despite the fact that in the past Jamuka had been infamously known to have boiled his opponent's generals alive. The rest of the Merkit clan that sided with the Naimans were defeated by Subutai, a member of Temüjin's personal guard who would later become one of the successful commanders of Genghis Khan. The Naimans' defeat left Genghis Khan as the sole ruler of the Mongol plains, which means all the prominent confederations fell and/or united under Temüjin's Mongol confederation. Accounts of Genghis Khan's life are marked by claims of a series of betrayals and conspiracies. These include rifts with his early allies such as Jamuka (who also wanted to be a ruler of Mongol tribes) and Wang Khan (his and his father's ally), his son Jochi, and problems with the most important Shaman who was allegedly trying break him up with brother Qasar who was serving Genghis Khan loyally. Many modern scholars doubt that all of the conspiracies existed and suggest that Genghis Khan was probably inclined towards paranoia as a result of his experiences.[citation needed]
His military strategies showed a deep interest in gathering good intelligence and understanding the motivations of his rivals as exemplified by his extensive spy network and Yam route systems. He seemed to be a quick student, adopting new technologies and ideas that he encountered, such as siege warfare from the Chinese. Many legends claim that Genghis Khan always was in the front in battles, but these may not be historically accurate.
As a result by 1206 Temüjin had managed to unite the Merkits, Naimans, Mongols, Uyghurs, Keraits, Tatars and disparate other smaller tribes under his rule. It was a monumental feat for the "Mongols" (as they became known collectively), who had a long history of internecine dispute, economic hardship, and pressure from Chinese dynasties and empires. At a Kurultai, a council of Mongol chiefs, he was acknowledged as "Khan" of the consolidated tribes and took the new title Genghis Khan. The title Khagan was not conferred on Genghis until after his death, when his son and successor, Ögedei took the title for himself and extended it posthumously to his father (as he was also to be posthumously declared the founder of the Yuan Dynasty). This unification of all confederations by Genghis Khan established peace between previously warring tribes and a single political and military force under Genghis Khan.
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1206 formed from many differing tribes. Genghis proclaime Khakhan
1209 Forces surrender of Xixia
1215 Mongols capture Beijing, seat of Jin Empire (Northern China)
central to capturing beijing was the defection of Ming-tan, he put out all of the Jin's commanders plan on the table
1218: Destroys the Kara-khitai empire by fermenting internal revolt. This was because the emperor of Kara Khitai was a Naiman (not a khitan), and seizing this main weakness, managed to get the entire empire crumbling before they struck the final blow.
1221: Destroys the Khwarezmian Empire (present day Iran) after the Shah decided to kill 2 trade mission that he sent. This was the most brutal campaign (in terms of punishment Genghis meted out), and was the one that history remembers. The feat will only later be surpassed by ironically the Germans.
1223: Mongol Empire finally ventures into Eastern Europe, wins Battle of Kalka river.
1227 Genghis Khan passed away (he technically had around 20 years to continue his legacy)
1237 (+30 years after unification): Subjugates Bulgaria and Kievan Russia. Lasts until 1480, to give a comparison, in order for Bismarck to have done the same, Germany would have to stretch all the way into Mongolia and hold it until 2240 AD. They couldn't even get past the Somme.
The mongol state still exists today. It was at its largest extent more than 200 years after its formation by Genghis Khan. The german reich was born and split and reborn and split and reborn and its lasted 130 years