The name Hayde was recorded several times in the LDS records for the Wuerttemberg state in the 1600s. Entries were also found for similar spellings in most of the other German states.
The earliest event recorded was the birth of a Nickel Heyde in 1356 at Sommerfeld, Lausitz (just west of Berlin), Prussia. Berlin at that time was merely the chief city of the small electorate of Brandenburg.
Many of the entries relate to the 1600s and 1700s, however there is much variation in spellings and tracking families is difficult.
The church records for a Hayde family in the parish of Nuertingen, Wuerttemberg have been found. The earliest entry is for a Hans Haid who was born in 1525. He had 7 children. Many of his children, grand children and great grandchildren died in 1635 when the plague hit this part of Germany. One of his descendants, a Carl Hayde, renounced his citizenship in 1812 (during the Napoleonic wars) and moved east to what is now Slovakia. Others in the family remained in Germany while some emigrated west in the 1760s, 1830s and 1860s. This is Tree #13 on my list. Descendants are currently living in Hungary, Germany, America and Australia.
More information on this family can be found at www.karlhayde.com. A DNA analysis of one of the descendants from this family shows no resemblance to mine (ie Tree #1) or any other Irish family members tested.
I have searched the records of a Hayde family in Groetzingen (2kms from Nuertingen). These cover a period from 1597 to the early 1700s. No subsequent records have been found for the family in the area because the surviving males probably emigrated to America. The American records however show that this family dropped the “e” in America and used Heyd and Hayd.
I have also searched some other German parishes however I have not yet found any Hayde descendant from these records. It is very hard to trace a family through these records. The handwriting is difficult to read, the language is foreign and several variants are used for the same people.
While the name Hayde can be found mainly in the Wuerttemberg state, its variants were in most other German states. During the Middle Ages (AD 400-1500), the variants were mainly in Bavaria , where the name Heidt was associated with the tribal conflicts of the area. This family prospered in the region of Augsburg throughout the early Middle Ages. Bavaria was ruled by the Wittelsbach dynasty from 1180 until 1918 when Germany became a republic.
It seems however that the German Hayde name has originated from around the Palatine/Baden-Wuerttemberg/Bavaria/Rheinland area of Germany in the 1500s. Emigration had then been eastwards (to Poland and what was Hungary) as well as westwards (to England, France,and America). I can find no link between the German and Irish Hayde families.
 As reported by the Swyrich Corporation on the Hayd coat of arms.