Tsuchigumo (土蜘蛛; also written 土雲, literally "dirt/earth spider") is a historical Japanese derogatory term for renegade local clans, primarily during the Asuka, Nara, and early Heian periods, and also the name for a race of spider-like yōkai in Japanese folklore. Alternative names for the historical groups include kuzu (国栖), and for the mythological Tsuchigumo, yatsukahagi (八握脛; roughly "eight-grasp shins," referring to their long legs) and ōgumo (大蜘蛛; "giant spider"). In the Kojiki and Nihon Shoki, the name was phonetically spelled with the four kanji 都知久母 (for the four morae tsu-chi-gu-mo). References to "tsuchigumo" appear in the chronicles associated with Emperor Jimmu, Emperor Keiko, and Empress Jingū, and these words were frequently used in the Fudoki (ancient reports on provincial culture, geography, and oral tradition) of various provinces, including Mutsu, Echigo, Hitachi, Settsu, Bungo, and Hizen.

The term "Tsuchigumo" (earth/dirt spider) is believed to be derived from an older derogatory term, tuchigomori (土隠), meaning "those who hide in the ground". This name likely referred to the fact that many of these clans utilized existing cave systems or built fortified dugouts and earthworks (Japanese: 土窟; tsuchi-muro or iwa-muro) in which to live and defend themselves. The term was used by the Yamato court as a generalized pejorative against chieftains and clans who would not submit to Imperial authority, regardless of their ancestry or location. They were often described in official records like the Nihon Shoki and various Fudoki as possessing "the nature of a wolf, the heart of an owl", being violently resistant, and dwelling in mountain caves or earthen fortifications. Some descriptions portrayed them as having abnormal physical characteristics; the "Jimmu" chapter of the Nihon Shoki describes them as "short in stature but long in limbs, similar to pygmies (侏儒)", while an excerpt from the lost Echigo Fudoki mentions Tsuchigumo with "shins eight 'tsuka' [hand-breadths] long, and possessing great strength." These descriptions likely served to dehumanize these groups and emphasize their "otherness" from the perspective of the Yamato state.

Historian Sōkichi Tsuda (ja) pointed out that, unlike terms like Kumaso and Emishi which referred to distinct groups, "Tsuchigumo" as used in the Fudoki often appears as the designation for specific individuals rather than entire peoples. Historian Yoshiyuki Takioto (ja) further suggests that these individuals were likely local chieftains whose power stemmed from shamanistic authority. This is supported by accounts in the Kyushu Fudoki where certain Tsuchigumo figures appear as priests or mediums involved in agricultural rituals or appeasing angered deities (kami).

The transformation of the Tsuchigumo into a monstrous, giant spider-like yōkai occurred during the Japanese medieval period (late 12th to early 17th centuries). One of the earliest and most influential depictions is found in variant texts of The Tale of the Heike, particularly the "Sword Scroll" (tsurugi-no-maki), which was compiled in the early 13th century. In this version, the creature is called a yamagumo (山蜘蛛, "mountain spider"), and its defeat by the hero Minamoto no Yorimitsu gives rise to the legend of his sword, Kumo-kiri ("Spider-Cutter"). As depictions evolved through later periods, the Tsuchigumo became increasingly bizarre and monstrous. The 14th-century emakimono (picture scroll) Tsuchigumo Sōshi portrays it as a colossal monster, and stories involving its extermination often feature Yorimitsu and his legendary retainer Watanabe no Tsuna, heroes also famous for defeating the powerful oni Shuten-dōji. The yōkai Tsuchigumo became a popular subject in Noh theatre, Jōruri puppet plays, and Kabuki. The historical Tsuchigumo have no direct connection to the actual ground spider species Jigumo (Antrodiaetus japonicus). Similarly, the modern Japanese common name for tarantulas (Ōtsuchigumo-ka, オオツチグモ科, Theraphosidae) which was inspired by the mythological creature has no historical link, as tarantulas are not native to Japan.

References to Tsuchigumo appear across Japan, indicating the term was applied to various local powers resisting Yamato authority. Historical records mention Tsuchigumo in at least seven locations in Hitachi province, six in Bungo, twelve in Hizen, two in Mutsu, and one in Hyūga, primarily in Kyushu, Tōhoku, and Kantō regions. Around 45 individual chieftain names associated with Tsuchigumo are recorded, among which 14 include titles like "me" (女, woman), "hime" (姫/媛, princess), suggesting female leadership was not uncommon, particularly in Hizen. Examples include Ōyamada-me (大山田女), Sayamada-me (狭山田女), Yasome (八十女), and Hayakitsu-hime (速来津姫). The Hitachi no Kuni Fudoki explicitly states that "Kuzu" and "Tsuchigumo" were synonymous terms in that region.

The Tsuchigumo of the Katsuragi region in Yamato Province (modern Nara Prefecture) are particularly well-known. According to the Nihon Shoki, Emperor Jimmu defeated several Tsuchigumo groups during his eastward expedition. These included figures named Niki Tobe (新城戸畔) at Hataoka-no-saki, Kose Hafuri (居勢祝) at Wani-no-saka-no-shita, and Ihafuri (猪祝) at Hetsugi-no-nagae-no-oka-no-saki. He is also said to have defeated Tsuchigumo at Takaowari village by weaving a net of katsura vines (葛), subsequently renaming the area Katsuragi (葛城). The Tsuchigumo of Takaowari were described as having small bodies and long limbs. Katsuragi Hitokotonushi Shrine (葛城一言主神社) features a "Tsuchigumo塚" (tsuka, mound), said to be where Jimmu buried the head, body, and feet of captured Tsuchigumo separately to prevent their vengeful spirits (onryō) from harming the living.

A unique physical characteristic attributed to the indigenous people of Yamato in early chronicles was the possession of tails. The Nihon Shoki describes the ancestor of the Yoshino no Futo (吉野首) clan as "glowing, with a tail", and the ancestor of the Yoshino no Kuzu (国樔) as "having a tail and pushing aside rocks". Similarly, the Kojiki refers to the people of Osaka (忍坂, modern Sakurai city) as "Tsuchigumo who have tails grown." These descriptions likely served to portray the pre-Yamato inhabitants as non-human or primitive.

Several accounts detail conflicts during the reign of Emperor Keiko (traditionally 71–130 AD):