Edo (江戸; lit. 'bay-entrance'; English: ; Japanese: [è̞.dó̞]), also romanized as Jedo, Yedo or Yeddo, is the former name of Tokyo.
Under the Tokugawa shogunate, Edo developed into a major early-modern urban centre with a population that is believed to have exceeded 1 million by the early 18th century — making it, by many estimates, the largest city in the world at the time.
Edo’s population and urban footprint expanded significantly due to deliberate policies, including land reclamation around Edo Bay, planned street layouts, large samurai residential areas, and an extensive system of waterways supporting transportation and commerce. The city was home to samurai officials, townspeople (chōnin), and artisans, and served as a centre of economic activity, urban cultural practices, and administrative organization during the Tokugawa era.
Following the overthrow of the Tokugawa shogunate in 1868, the city formerly known as Edo was renamed Tōkyō ("Eastern Capital"), and the emperor’s residence was moved there from Kyoto, establishing Tokyo as the capital of Japan. The development of Edo during the Tokugawa period (1603‑1868) influenced the later growth and urban character of Tokyo after the Meiji Restoration.
Before the 10th century, there is no mention of Edo in historical records, but for a few settlements in the area. That name for the area first appears in the Azuma Kagami chronicles, which have probably been used since the second half of the Heian period. Edo's development started in the late 11th century with a branch of the Kanmu-Taira clan (桓武平氏) called the Chichibu clan (秩父氏) coming from the banks of the then-Iruma River, present-day upstream of the Arakawa river. A descendant of the head of the Chichibu clan settled in the area and took the name Edo Shigetsugu (江戸重継), likely based on the name used for the place, and founded the Edo clan. Shigetsugu built a fortified residence, probably around the edge of the Musashino Terrace, that would become Edo castle. Shigetsugu's son, Edo Shigenaga (江戸重長), took the Taira's side against Minamoto no Yoritomo in 1180 but eventually surrendered to Minamoto and became a gokenin for the Kamakura shogunate. At the fall of the shogunate in the 14th century, the Edo clan took the side of the Southern Court, and its influence declined during the Muromachi period.
In 1456, a vassal of the Ōgigayatsu branch of the Uesugi clan started to build a castle on the former fortified residence of the Edo clan and took the name Ōta Dōkan. Dōkan lived in the castle until his assassination in 1486. Under Dōkan, with good water connections to Kamakura, Odawara and other parts of Kanto and the country, Edo expanded as a jōkamachi, with the castle bordering a cove (now Hibiya Park) opening into Edo Bay, and the town developing along the Hirakawa River running into the cove, and on Edomaeto (江戸前島), the stretch of land on the eastern side of the cove (now roughly where Tokyo Station is). Some priests and scholars fleeing Kyoto after the Ōnin War came to Edo during that period.
After the death of Dōkan, the castle became one of strongholds of the Uesugi clan, which fell to the Later Hōjō clan at the battle of Takanawahara in 1524, during the expansion of their rule over the Kantō area.
When the Hōjō clan was finally defeated by Toyotomi Hideyoshi in 1590, the Kanto area was given to rule to Toyotomi's senior officer Tokugawa Ieyasu, who took his residence in Edo.
Ieyasu's initial urban vision and the transformation of an unformed settlement (1590–1603)
When Tokugawa Ieyasu first entered Edo in 1590, the area was not yet a town or city in any meaningful sense. What existed was a small fortified residence—commonly called “Edo Castle” (Edo-jō)—consisting of only a handful of (small) buildings standing on the edge of the Musashino Plateau. To the east of the residence stretched nothing but wetlands, tidal inlets, marshes, and patches of undeveloped wasteland. There was no urban district, no planned streets, and no concentrated population.
Recognizing the strategic potential of the site, Ieyasu immediately initiated surveys of the surrounding topography, focusing on the plateau, the Hibiya inlet（日比谷入り江）, and the low-lying marshland east of the "castle". These surveys formed the basis of his first deliberate urban plan. Under his direction, early engineering works began: preliminary modification of the Hibiya inlet, initial attempts to redirect the Hirakawa River, and the earliest stages of constructing outer moats and functional canals.
Although large-scale land reclamation and restructuring would accelerate only after Ieyasu's victory at the Battle of Sekigahara in 1600, the fundamental conceptual blueprint for transforming Edo from an undeveloped landscape into a governable urban center was already established during this period. This development was not spontaneous or natural—Edo's growth began as an intentional political and military project shaped directly by Ieyasu's vision and administrative control.
Tokugawa Ieyasu emerged as the paramount warlord of the Sengoku period following his victory at the Battle of Sekigahara in October 1600. He formally founded the Tokugawa shogunate in 1603 and established his headquarters at Edo Castle. Edo became the center of political power and the de facto capital of Japan, although the historic capital of Kyoto remained the de jure capital as the seat of the emperor. Edo grew from a fishing village in Musashi Province in 1457 into the largest metropolis in the world, with an estimated population of 1 million by 1721.
The Great Reconstruction (1603–1630s)
After the shogunate was firmly established and especially after 1615, the Tokugawa regime undertook massive expansion works under Tenka-Bushin (天下普請) :
Expansion of Edo Castle into one of the largest fortified complexes in the world
Large-scale cutting of the Musashino Plateau for earth
Reclamation of coastlines throughout Edo Bay (Nihonbashi, Kyōbashi, Tsukiji, etc.)