The following announcement was written by MyHeritage:

We are pleased to announce the publication of three important Welsh historical record collections on MyHeritage: Wales, Parish Births and Baptisms; Wales, Parish Marriages and Banns; and Wales, Parish Deaths and Burials. The collections consist of 14.8 million indexed historical records and cover over 450 years of Welsh history. High quality scans of the original documents will be added very soon. These collections are the only source of genealogical information in Wales before the 19th century, making them an invaluable resource for anyone researching their Welsh heritage. 

Here are more details about the new Welsh collections:

Wales, Parish Births and Baptisms	An index of births and baptism records in Wales from 1538 to 1920.	8,242,549 records	Search collection now
Wales, Parish Marriages and Banns	An index of marriages and banns in Wales from 1539 to 1935.	3,480,047 records	Search collection now
Wales, Parish Deaths and Burials	An index of deaths in Wales from 1539 to 2005.	3,149,924 records	Search collection now

In 1537, the Church of England mandated the keeping of parish registers of all births and baptisms, marriages, and deaths in Wales. For nearly three centuries these records were the only vital records documented in Wales. In 1837, civil registrations of births & baptisms, marriages, and deaths were required throughout all of England and Wales. These records are already on MyHeritage and can be found in our U.K. collections.

Unlike most countries where civil registrations replaced parish records, Wales parish records continue to be recorded. These collections contain records as recent as 2005, making the Wales Parish collections some of the longest spanning collections on MyHeritage.

Parish baptisms, marriages, and burials were all recorded in a single volume until 1774, at which point the law changed to require a separate marriage register and another one for marriage banns (proclamations of an intent to marry). Standardized forms for these registers appeared in 1812. 

The amount of information in registers varies from parish to parish. Later records generally give more complete information than earlier ones. Some early parish registers are in Latin. A few very early registers are in Welsh or have occasional entries in Welsh. Local dialects may have affected the spelling of names or places. 

The records may use the patronymic naming system. This system started in Wales in the 15th century and continued through the mid-18th century. In Wales, this usually involved adding ‘ab’ or ‘ap’ between the child’s first name and the father’s first name. For example, Dylan ap Lewis is Dylan son of Lewis.

The collections aren’t limited to members of the Church of England, and other religious denominations often registered life events with their local parish. 

Wales, Parish Births and Baptisms

There is a lot more information available in the MyHeritage Blog at: https://blog.myheritage.com/2020/10/myheritage-releases-three-historical-record-collections-from-wales/.