阴土兔年 (female Earth-Rabbit) 1526 or 1145 or 373 — to — 阳金龙年 (male Iron-Dragon) 1527 or 1146 or 374
Year 1400 (MCD) was a leap year starting on Thursday (link will display the full calendar) of the Julian calendar. The year 1400 was not a leap year in the Proleptic Gregorian calendar, it was a common year starting on Wednesday. The leap year began on a Thursday, and it ended on a Friday. The common year began on a Wednesday, and ended on a Wednesday, but the leap year ran from the Thursday to the Friday. The Wednesday at the beginning is January 1, the Wednesday at the end is December 31. It was the 1400th year of the Common Era and Anno Domini designations, the 400th year of the 2nd millennium, the 100th and last year of the 14th century, and the first year of the 1400s.
March 23 – Five-year-old Trần Thiếu Đế is forced to abdicate as ruler of Đại Việt (modern-day Vietnam), in favour of his maternal grandfather and court official Hồ Quý Ly, ending the Trần dynasty after 175 years and starting the Hồ dynasty. Hồ Quý Ly subsequently changes the country's name to Đại Ngu.
April 25 – Jingnan campaign: In the Shandong province of Ming dynasty China, Zhu Di, Prince of Yan, defeats the Imperial forces of General Li Jinglong in the two-day Battle of Baigou River, by taking advantage of the chaos that results when a gust of wind breaks the staff of General Li's flag of battle. The Yan forces capture 100,000 of the Imperial soldiers as prisoners and Li and the others retreat to Jinan.
April – King Swa Saw Ke, of Ava, the largest kingdom in Burma, dies after a reign of 33 years and is succeeded by his son, King Tarabya, who reigns less than seven months before being assassinated.
June 5 – Duke Frederick I of Brunswick-Lüneburg is assassinated after being identified as a rival to Wenceslaus, Holy Roman Emperor. Frederick, on his way back from a May 22 meeting of the prince-electors, is ambushed by a party of men led by Count Henry of Waldeck while passing through the village of Kleinenglis in the Principality of Waldeck and Pyrmont (now part of the German state of Hesse, near Borken).
July 26 – Jagiellonian University is re-established in Kraków by order of King Władysław II, with the creation of the Faculty of Theology at what is then called the Kraków Academy. The restoration is partially financed by the sale of jewelry owned by the King's late wife, Queen Jadwiga, who had died in 1399.
August 6 – Writing from Newcastle upon Tyne to Scotland's King Robert III, England's King Henry IV sends a demand that King Robert meet him "on Monday the 23rd of this present month of August, at Edinburgh, where, for this reason and for the peace of tranquility of the realms of England and Scotland, we intend to be," for Robert "to perform the obligation which you owe us" as "overlords of Scotland and of its kings in all temporal matters pertaining to them..." King Henry warns that "considering the effusion of Christian blood and other dangers and losses which may occur if you do not comply with our wishes, you will be present to render us homage and take the oath of fealty." [1]
August 14 – King Henry IV leads the English Army into Scotland, after receiving no answer from Scotland's King Robert III to his August 6 demand. The troops reach Haddington, East Lothian the next day and at Leith, on the outskirts of Edinburgh, by August 18. As historian James Hamilton Wylie will note almost 500 years later, "the walls of Edinburgh did not fall before this ram's-horn blast, and August 23rd came and went without the required homage or recognition."[2]
August 20 – Meeting at the Lahneck Castle in what is now the German state Rhineland-Palatinate, the princes of the German states vote to depose the Holy Roman Emperor, Wenceslaus, due to his weak leadership and mental illnesses.
October 7 – Tamerlane, the Mongol conqueror, stops between Malatya and Aleppo at the Turkish garrison in Behesna. According to author Peter Purton, the garrison "had the temerity to shoot a catapult ball at Timur which rolled into his tent. Setting up his own battery of 20 machines, it is said that the first shot hit and destroyed the offending weapon. Treating this as a good omen, the attack was launched, the towers mined... and the place surrendered."[3]
November 2 – The Mamluk Sultanate surrenders the city of Aleppo and Tamerlane's Army massacres many of the inhabitants.[5]
November 25 – (9th waxing of Nadaw, 730 ME) Minkhaung I becomes the new King of Ava, the largest kingdom in what is now northern Myanmar, after a battle for power that follows the assassination of the erratic King Tarabya.
December 25 – In China, the Jingnan campaign of Prince Zhu Di of Yan suffers a serious reversal at the Battle of Dongchang as Imperial General Sheng Yong, replacement of Li Jinglong, encircles the Yan forces. Yan Army General Zhang Yu is killed, but Zhu Di is able to escape to the northern capital at Beijing and regroups his forces for a second attack to take place in February.
In modern-day Korea, King Jeongjong of Joseon abdicates in fear of an attack by his ambitious younger brother, Taejong. Taejong succeeds to the throne.