Magnates and their honours · The Kamakura house and its housemen · as at first light, 1 January 1200

Chiba Tsunetane

The Chiba are the oldest of the east's great Taira houses and the house that, with the Miura, made Yoritomo's rising possible: when he came to Shimōsa after Ishibashiyama and the sea crossing to Awa, Tsunetane received him and told him to settle at Kamakura (English Wikipedia: Chiba clan).

Their home is Chiba on the edge of Tokyo bay (Inohana), their province Shimōsa, and their strength the lands and sea-landings of the Bōsō coast and the Katori inland sea; the crossing of the Sumida in 1180 was made with boats from the Chiba and Kasai side (Azuma Kagami, recalled). Tsunetane is the doyen of the housemen and in his eighties; his six sons hold branch lands from Sōma in the north of Shimōsa to Ōsuga in the south-east. The Chiba are on the winning side of the winter: the party of Miura, Chiba, Hatakeyama, Wada, Oyama and Yūki that has brought Kajiwara down (the heads of the houses named in the Azuma Kagami's story of the petition are recalled, not re-read).

Who he is

Name
Chiba Tsunetane
Title
Head of the Chiba house (tōryō) and constable (shugo) of Shimōsa
Since
He met Yoritomo in the autumn of 1180 in Shimōsa after Yoritomo's landing in Awa and advised him to make Kamakura his base (English Wikipedia: Chiba clan); the constable's post of Shimōsa dates from the settlement of 1185 or later (recalled, not pinned)
Born
1118 (Gen'ei 1, recalled): about 81 by the Western count and 82 or 83 by the Japanese; on the likely course he dies in the third month of Kennin 1 (about April 1201, recalled)
Family
Of the Taira of the Kanmu line. The English page says his lands passed to six sons, the Chiba rokutō, and names none; the branches are recalled as Chiba, Sōma, Takeishi, Ōsuga, Kokubun and Tō. Which son or grandson leads the house in the field on 1 January 1200 is not pinned.
Confidence
medium

English Wikipedia (Chiba clan: home province Shimōsa, base at Inohana from 1126, hereditary constable of Shimōsa under Kamakura, advised Yoritomo to make Kamakura his base). Mass from memory. ja.wikipedia was refused.

Overlord

Minamoto no Yoriie, as head of the housemen; the court's governors of Shimōsa in law

What it holds

  • The home lands round Chiba (Inohana) on the bay shore, the oldest seat
  • The constable's post of Shimōsa (the capital guard, the pursuit of rebels and murderers, the call-out of housemen; no right over the court's estates)
  • Branch lands in the north of Shimōsa on the Sōma side and in the south-east at Ōsuga, Takeishi and Kokubun (recalled)
  • Stewardships (jitō) in lands far from home that the English page says Tsunetane acquired 'across Japan' (not itemised)

How it was acquired

By descent; enlarged by Yoritomo's grants after 1180, 1185 and 1189.

Allies and rivals

Allies: the Miura (the pairing of Miura and Chiba is the old Taira core of the housemen), Kasai (their neighbour and boat partner), the Hōjō. Past rivals: the Satake (crushed 1180), Kazusa Hirotsune (killed 1183, Chiba's neighbour in Kazusa). Present watchers: the Hiki, whom the old guard distrust.

How things stand that morning

Quiet strength. Tsunetane is old and the heads of his branches act for him. The house is among those that wrote or signed the petition against Kajiwara and gains by his fall, since Kajiwara's party would have chipped at the old Taira houses' independence.

Wealth

Rice and salt of the Shimōsa coast, fisheries and boats on the bay and the Katori sea, the tolls of the river landings. No figure.

Military

Mounted housemen of the home district and the branches, boats on the bay; no numbers (the Azuma Kagami's counts of 1180 are not repeated).

Threats

  • Tsunetane's age: his death ends a generation
  • The Hiki, who hold Shinano and Kōzuke and the heir's ear
  • Court appointments to Shimōsa that cut across the constable's rights

What the year holds

What happened next, if nothing in play changes it. Each event carries what it depends on and what would stop it.

  1. Kennin 1/3 (about April 1201, recalled)Tsunetane dies in his eighties and the Chiba lands go to his sons and grandson (the Chiba rokutō).Depends on: Natural death Stopped by: Nothing in play stops a natural death; only a change in the person's circumstances (illness cured, flight, removal) alters the date, and the campaign rules on that.
  2. Kennin 3 to Genkyū 2 (1203 to 1205)The Chiba side with the Hōjō in the Hiki and Hatakeyama quarrels (recalled, not checked).Depends on: Hōjō supremacy Stopped by: A Hiki victory

Where the sources disagree

  • The campaign board's 'Chiba (Chiba clan)' point at 35.607 140.106 is the old Inohana seat of the English page: accepted.

Evidence: One short English page, Mass and the brief; the sons' names and the 1201 date are recalled.

"The campaign board" is OMNIA's working map. These notes record where its earlier claims were checked against the sources.

On the map: Only the home district is drawn; the constable's post covers the whole of Shimōsa but gives rights over men, not over ground.

Primary sources for Kamakura regime

Chronicles, registers, sagas and inscriptions written in or near 1200 that cover this entry. Each has its own page with editions, translations and where to read it.

  • Hundred Times Refined Extracts: court annals (late thirteenth century, from court diaries). Short dated annals of the imperial court excerpted from courtiers' diaries, among them the Gyokuyo and the Meigetsuki. Read online
  • Mirror of the East, Anonymous; compiled by officials of the Kamakura shogunate (compiled about 1300 from the shogunate's records, diaries and family documents). The Kamakura house's own chronicle, in daily entries. Read online
  • Jottings of a Fool: an interpretative history of Japan, Jien (慈円) (about 1219 to 1220, revised to about 1223). A history by Kujo Kanezane's brother, head of the Tendai school and the leading churchman of the court, written to explain the fall of the Kujo and the rise of the warriors as the working of principle (dori). Read online
  • Diary of the Inokuma Regent: the diary of Konoe Iezane, Konoe Iezane (近衛家実) (1197 to 1218, as a daily diary). The diary of the regent's heir, aged twenty-one in 1200 and already a senior courtier under his father Konoe Motomichi, who was regent (sessho) for the child emperor Tsuchimikado. Read online
  • Leaves of Jade: the diary of Kujo Kanezane, Kujo (Fujiwara) Kanezane (九條兼實) (1164 to 1200, as a daily diary). The diary of the former regent, Yoritomo's ally at court, who had been driven from power in the Kenkyu purge of 1196 and lived in retirement in 1200. Read online
  • Record of the Bright Moon: the diary of Fujiwara no Teika, Fujiwara no Teika (藤原定家) (1180 to 1235, as a daily diary, with gaps). The diary of the poet and courtier, then thirty-eight and a middle-ranking official of the Kujo house. Read online
  • Surviving Documents of the Kamakura Period, Various; collected by Takeuchi Rizo (竹内理三) (documents of 1185 to 1333, collected and printed 1971 to 1997). The collected charters, deeds, court orders, shogunal directives, temple records and land registers of the Kamakura age, printed in date order. Read online
  • The Tale of the Heike, Anonymous; traditionally attributed to Shinano no Zenji Yukinaga, performed and reshaped by blind reciters (early thirteenth century in its first form; the standard Kakuichi text was fixed in 1371). The epic of the Genpei war, in the form the reciters gave it over the century after 1200. Read online

Sources and studies

  1. KJA_BRIEF.md and the OMNIA board for sheet kja (the lead's notes: [own] computation, [not yet checked against the source] recollection, [en] English Wikipedia)
  2. Azuma Kagami (the Kamakura chronicle), Kenkyu 10 to Shoji 2 entries, recalled and through the brief; ja.wikipedia and ja.wikisource were refused in this session, so no entry was re-read
  3. Jeffrey P. Mass, Warrior Government in Early Medieval Japan (1974), from memory; the archive.org full text could not be opened
  4. English Wikipedia: Chiba clan (read this session; thin)

Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.