A commote (Welsh cwmwd, sometimes spelt in older documents as cymwd, plural cymydau, less frequently cymydoedd)  was a secular division of land in Medieval Wales. The word derives from the prefix cym- ("together", "with") and the noun bod ("home, abode").  The English word "commote" is derived from the Middle Welsh cymwt. 
The basic unit of land was the tref, a small village or settlement. In theory, 100 trefi made up a cantref (literally, "one hundred settlements"; plural: cantrefi), and half or a third of a cantref was a cymwd, although in practice the actual numbers varied greatly. Together with the cantrefi, commotes were the geographical divisions through which defence and justice were organised. In charge of a commote would be a chieftain probably related to the ruling Prince of the Kingdom. His court would have been situated in a special tref, referred to as a maerdref. Here, the bonded villagers who farmed the chieftain's estate lived, together with the court officials and servants.  Commotes were further divided into maenorau or maenolydd.
The Domesday Book has entries for those commotes that in 1086 were under Norman control, but still subject to Welsh law and custom. However, it refers to them using the Anglo-Norman word "commot" instead of hundred [ citation needed ], the word used at the time for the equivalent land division in England. The commotes mentioned in the Domesday Book, in general, represented recent Anglo-Norman advances into Welsh territory. Although the commotes were assessed for military service and taxation, their obligations were rated in carucates (derived from Latin for cattle or oxen), not in hides as on the English side of the border.
The customs of the commotes are described in the Domesday accounts of the border earldoms of Gloucestershire, Herefordshire, Shropshire and Cheshire. The principal commotes described in Domesday were Archenfield, Ewias, and the commotes of Gwent in the south; Cynllaith, Edeirnion, and Iâl (Shropshire accounts); and Englefield, Rhos and Rhufoniog (Cheshire accounts).
In legal usage, the English word 'commote' replaced cwmwd following the Edwardian conquest of Wales in the 13th century, when English was made the official language for all legal documents. The Welsh, most of whom knew not a word of English, naturally continued to use cwmwd and still do so today. In much of Wales, commotes had become more important than cantrefi by the mid-13th century and administration of Welsh law became the responsibility of the commote court rather than the cantref court. Owain Glyndŵr called representatives from the commotes for his two parliaments during the rising of 1400–1409.
The boundaries of commotes, or in some cases cantrefi, were in many cases subsequently more accurately represented by church rural deaneries than by the hundreds issuing from the 16th century Acts of Union.
A considerable number of the names of adjacent medieval Welsh commotes contain is (meaning "lower", or "below" as a preposition) and uwch (originally uch and meaning "higher", or "above" as a preposition), with the dividing line between them being a natural boundary, such as a river, mountain or forest. Melville Richards noted that, in almost every instance where this occurs, the point of central authority was in the "is division" when the commote was named, and he suggested that such commotes were originally named in the sense of 'nearer' and 'farther' based on the location of that central authority—i.e., the terminology is for administrative purposes and not a geographical characterisation. 
Richards attributed the use of is and uwch to some confusion in translating Latin sub (meaning "lower") and supra (meaning "upper") into Welsh in too literal a sense, when the proper sense was to consider sub to be an administrative synonym for Latin cis (meaning "this side of"), and to consider supra to be an administrative synonym for Latin trans (meaning "the other side of"). 
A number of smaller units, such as manors, parishes and townships, also use the administrative distinction of is and uwch, sometimes in their Latin forms (e.g., the manor of Clydach in Uwch Nyfer, divided into Sub Clydach and Ultra (Supra) Clydach). 
This is unrelated to the common use of isaf and uchaf in farm names, where the terms are used in the geographical sense. 
The Red Book of Hergest (1375–1425) provides a detailed list of commotes in the late 14th and early 15th centuries.  The list has some overlaps and is ambiguous in parts, especially in the Gwynedd section. It should also be borne in mind that the number and organisation of the commotes was different in the earlier Middle Ages; some of the units and divisions listed here are late creations. The original orthography of the manuscript is given here together with the standard modern Welsh equivalents.
Montgomeryshire is one of thirteen historic counties and a former administrative county of Wales. It is named after its county town, Montgomery, which in turn is named after one of William the Conqueror's main counsellors, Roger de Montgomerie, who was the 1st Earl of Shrewsbury.
A cantref was a medieval Welsh land division, particularly important in the administration of Welsh law.
The Kingdom of Dyfed, one of several Welsh petty kingdoms that emerged in 5th-century sub-Roman Britain in southwest Wales, was based on the former territory of the Demetae. The medieval Irish narrative, The Expulsion of the Déisi, attributing the kingdom's founding to Eochaid, son of Artchorp, being forced across the Irish sea, in the 5th century; his descendants founding the line of the kings of Dyfed, down to "Tualodor mac Rígin". The Normans invaded Wales, and by 1138 incorporated Dyfed into a new shire called Pembrokeshire after the Norman castle built in the Cantref of Penfro and under the rule of the Marcher Earl of Pembroke.
Llywarch ap Llywelyn was an important medieval Welsh poet. He is also known by his bardic name, "Prydydd y Moch".
The Hundred of Cilgerran was a hundred in the north of Pembrokeshire, Wales. It was formed by the Act of Union of 1536 from the commote of the pre-Norman cantref of Emlyn included by the Act in Pembrokeshire and is otherwise called in Welsh Emlyn Is Cuch, with the addition of the Cemais parish of Llantood. The area of the commote was about 106 km2: that of the hundred was 113 km2.
The Hundred of Dungleddy was a hundred in the centre of Pembrokeshire, Wales. It had its origins in the pre-Norman cantref of Deugleddyf. It derives its Welsh name from its position between the two branches of the River Cleddau (Cleddyf): the English form is a corruption of the Welsh. The area of the cantref was around 185 km2: it was the smallest of the seven cantrefi of Dyfed.
Cemais Is Nyfer was a mediaeval commote in the Dyfed cantref of Cemais, Wales. It consisted of the territory between the rivers Nyfer and Teifi, and comprised the parishes of Eglwyswrw, Monington, St Dogmaels, Llanfair-Nant-Gwyn, Llantood, Moylgrove and Bayvil, and parts of Nevern and Meline in what is now Pembrokeshire. Its area was about 100 km2 and its civil and ecclesiastical headquarters were at Nevern.
Cemais Uwch Nyfer was a mediaeval Welsh commote in the Dyfed cantref of Cemais, in what is now Pembrokeshire. It consisted of the territory between the Afon Nyfer and Fishguard, and its civil headquarters were at Newport.
The Cantref of Penfro was one of the seven cantrefi of the Kingdom of Dyfed. It subsequently became part of Deheubarth in around 950. It consisted of the long peninsular part of Dyfed south of the Eastern Cleddau and the Daugleddau estuary, and bordered on its landward side by Cantref Gwarthaf. The name, meaning "land's end", derives from Pen and "fro". Its area was approximately 140 square miles (360 km2).
Cantref Gwarthaf was the largest of the seven cantrefi of Dyfed in southwest Wales. It subsequently became part of Deheubarth in around 950. It consisted of the southeastern part of Dyfed containing most of the basin of the River Tâf, parts of modern-day Pembrokeshire and Carmarthenshire.
Rhwng Gwy a Hafren was a region of medieval Wales, located in the Welsh Marches between Powys to the north and Brycheiniog to the south. It was bounded by the rivers Wye and Severn. It covered about the same territory as Radnorshire, now part of the county of Powys. The region first came into its own in the 9th or 10th centuries, when it was ruled by leaders who operated independently of the surrounding kingdoms. After the Norman invasion, it comprised the central part of the Welsh Marches and was the site of frequent struggles between Welsh and Norman forces.
Mechain was a medieval cantref in the Kingdom of Powys. This cantref has also been referred to as Y Fyrnwy (Vyrnwy). Mechain may owe its name to the River Cain which flows through it on its way to join the River Vyrnwy; 'Me' or 'Mach' may signify meadows or plain, in which case Mechain would mean "Meadows of the Cain". It corresponds to the later hundred of Llanfyllin.
Cwmdauddwr is a village in Powys, Wales. It is contiguous with the town of Rhayader on the opposite side of the River Wye. The village is located on the B4518 road linking Rhayader with the Elan Valley Reservoirs.
Caerwedros was a medieval commote in the south of the Kingdom of Ceredigion. With Mebwynion, Gwynionydd and Is Coed, Caerwedros was one of three cantref Is Aeron commotes.
Townships in Montgomeryshire are divisions of the ancient parishes of the county of Montgomery. In 1539 townships were grouped together in Hundreds. The Townships which were recognised were based on the older Welsh divisions of Tref, or plural Trefi, which had formed the Welsh administrative districts of the Commote. Not all of the former Tref were recognised and some smaller trefi were amalgamated into larger townships. A township was allocated to a particular parish—that is, one of the [civil] parishes of Wales, the predecessors to today's communities of Wales. The townships were recognised as administrative districts, rather than the parishes.
Caereinion was a medieval cantref in the Kingdom of Powys, or possibly it was a commote (cwmwd) within a cantref called Llŷs Wynaf. It was divided into the manors of Uwch Coed and Is Coed.
Ystrad Marchell sometimes Strad Marchell was a medieval commote (cwmwd) in the cantref of Ystlyg in the Kingdom of Powys. It roughly coincides with the parish of Welshpool.
Deuddwr was a medieval commote (cwmwd) in the cantref of Ystlyg in the Kingdom of Powys.