State · 851 – 939

Kingdom of Brittany

A state of 851 – 939 — 88 years in Europe. It was followed by Duchy of Normandy and Duchy of Brittany. Its line of rulers holds 2 people.

For the full story, the article on Wikipedia (CC BY-SA 4.0); this page holds what the record says of the state.

Stood: 88 years; 851 – 939
Rulers: 2; the Duke
Most ground: 47,300 km²; in 870

Map: Kingdom of Brittany in 870, its borders in gold among its neighbours — Kingdom of Brittany in 870, when it held the most ground the borders dataset draws for it: 47,300 km². Its neighbours wear their tints, as on the atlas's own map. Borders from Cliopatria (CC BY 4.0), coast and rivers from Natural Earth, cities from Reba, Reitsma & Seto 2016 (CC BY 4.0), each city under the name it bore that year.

Kingdom of Brittany in 825, first mapped — The rise and the fall in one frame: the same ground at the years the borders dataset first maps it, maps it largest, and last maps it.

Kingdom of Brittany in 870, at its largest — The rise and the fall in one frame: the same ground at the years the borders dataset first maps it, maps it largest, and last maps it.

Where it sits in time

Five thousand years, 3000 BCE to 2026; the state in gold, what it replaced or followed and what replaced or followed it in grey.

Before and after

The states the record files it as replacing or following, and those that replaced or followed it - Wikidata's own statements, each read from this state's side.

After it

Duchy of Brittany · followed by · 939 – 1547
Duchy of Normandy · followed by · 911 – 1259

Rulers

Read from the state’s own English article and its rulers’ articles, where Wikidata names no ruler.

ending not on record

Ruler	Reign	Length	How it ended · source	To the ruler before
Erispoe	851 – 857	6 years	ending not on record
Alan II, Duke of Brittany	938 – 939	1 year	ending not on record

2 rulers, 2 with terms dated as terms, covering 851 – 939. Median reign 3.5 years. 0 of 1 handovers irregular - a killing, a deposition, a rival claimant, a rising or a coup beside it. A blank in the last column means no kin on record, which is coverage, never “unrelated”.

Ground held, by year

km² inside its borders as the borders dataset draws them, measured on an equal-area grid; a step series, held between the years the dataset maps.

24,100 km² in 851, 45,700 km² in 921; at its largest 47,300 km² in 871. Cliopatria, CC BY 4.0.

Among all states

Each measure against the states that carry it, never against all of them: a bar is the share of those states below this one.

How long it stood88 years
stood longer than 44% of 3,187 states with a recorded end or still standing.
The most ground it held47,300 km²
held more ground at its peak than 34% of 1,465 states with a border in Cliopatria.
Wars recorded per centurynone
had more wars on record per century than 44% of 3,187 states, counting the wars the atlas hosts under each.
How long a reign lasted, at the median6 years
had longer reigns, at the median, than 22% of 967 states whose dated line can carry a median.
Rulers on record2
has more rulers on record than 34% of 1,968 states with a line of rulers.

What led to it, and what came of it

The investigation's own picture: 2 causes the record names and 2 results, the strongest six of each at their own years, joined to the state by the kind of claim - a recorded statement solid, the article's sentence dashed, a theory dash-dot.

in the articlelinked

Open the investigation: every row with its evidence, the conditions at the time, the theories condition by condition, and the succession analysed.

Open in the atlas

On the timeline, 841 – 949, with everything that stood beside it.
On the map in 870, live: scrub the year and watch its borders move.
Investigate it: what led to it, what came of it, and its succession analysed.

Wikidata Q771193 (CC0) · borders Cliopatria, CC BY 4.0 · coast and rivers Natural Earth · data built 2026-10-06 · Pastlas v2.9.1, by Oleh Voronko. The published atlas and its data are for non-commercial use.