There are a substantial number of family tree's on Ancestry that identify a couple by the name of David Cowan and Jane Wright. Unfortunately, there seems to be little agreement as to who this couple might be. Some have him born in 1726, some in 1740, some in 1753, plus others with a wide variety of dates in between. Some have David dying in Sevier County TN, some have him dying in Alabama, some in Georgia. At least there's concensus that he was born in Virginia and had a wife named Jane Wright.
Most likely there was an actual David Cowan born in 1726, and another born in 1740, and another born in 1753, etc. Various sources seem to have been used by different people to document the history of their particular David Cowan and his wife, and some have misapplied data for someone else by the same name. As a result, we have many different alternative realities for this couple reflected in the Ancestry Tree's. If you take the tree's at face value there are at least six distinct couples bearing these same names, all living in the the southeast US around the time of the Revolution. This is hardly likely. While there may have been more than one couple with these names, six seems improbable. Most likely there were a number of David Cowans living in this area, and one of them married a Jane Wright. But which one?
The following is concerned In particular with the identity of the David Cowan who lived in Sevier County TN from about 1786 until his death sometime after February 1811. This David Cowan is identified here as Person:David Cowan (1). Did David Cowan (1) marry Jane Wright?
There are several original sources that can be marshalled to show both the history of David Cowan (1), and the identity of his wife.
The best starting point for this is a land record in Washington County, VA, dated 1786.
David Cowan and wife Jane by deed dated January 30, 1786, recites. Between David Cowan late of the County of Washington of the first part and Charles Bickley of the other part— conveys a tract of land on the waters of the Clinch river.
A Certificate attached reads as follows:
This is to certify that we David Craig and John Clack two of the Justices for Sevier County, having received a Commission from the Court of Washington County to take the examination of Jane Cowan have according to said Commission this fourth day of April A. D. 1786 went to the house of David Cowan husband of said Jane Cowan etc."
These records clearly establish that the given name of David (1)'s wife was "Jane". They also establish David (1) came to Sevier County TN shortly after the Revolution from Washington County in Virginia. The property described is the parcel on which Cowan's Fort was located in Castle's Woods, along the east side of the Clinch River. This parcel was settled by David Cowan in 1769 when the area was first opened for settlement.
This gives us the basis for a short history of this David Cowan
We know from land records that he arrived in Castles Woods, Southwest Virginia in 1769.  He lived there until just after the Revolution, settling by 1786 in Sevier County, TN, dying there after February, 1811. Where was he prior to living in Castle's Woods?
Currently available evidence suggests that he was living in Albemarle County VA. The primary evidence for this is a 1759 land transaction in which a David Cowan sells a 268 acre tract of land in the Meachum River watershed.
19 May 1759 DAVID COWAN & wife JANE, planter, to JNO. COWAN for L10, 268 acres Mitchum River adj. HENRY CARR, WM. WALLACE. Wit: JOHN ANDERSON, JAS. COWAN, NICHL. WALLACE.
Since this record identifies the wife of this particular David Cowan as "Jane", we can at least say that this is consistent with identifying him as David Cowan (1). Its possible that he's a different David Cowan, also married to a "Jane". Circumstantial evidence, though supports the idea that he is indeed David (1). In particular, we know that about the time David (1) appeared in Castle's Woods in 1769, a person:David Gass (1) also appeared as a near neighbor. This David Gass came to the area from Albemarle County, where he had settled earlier in the Meachums River watershed. He is listed in the 1758 Militia Roster of Albemarle County. This David Gass is thought to be a kinsman, possibly a brothreinlaw to the Cowans of Caseles Woods (William, Samuel, and Andrew, though Andrew actually lived closer to Abingdon); Andrew is now believed to be David's brother, so that would make David Gass and David Cowan of Castle's Woods, kinsmen as well.  The idea that the Cowan's were kinsmen to David Gass is reinforced by the fact that at least three of them (David, William and Samuel's son John) moved to Madison County Kentucky living close to David Gass, at least for a short while, before settling in Sevier and Blount County TN. From this, it seems reasonable that the David Cowan who, together with wife Jane, sold his land in Albemarle County in 1759, is in fact David Cowan (1) who eventually settled first in Castle's Woods and then in Sevier County.
The basis for identifying David Cowans wife as "Jane Wright" seems to be the following record:
Wright vs. Wright--O. S. 148; N. S. 51--Bill, 11th September, 1805.....David Cowan, aged 55 years, deposes in Jefferson County, 8th November, 1808. David married James Wright's sister....Source:Chalkley's Chronicles
From this we know that this particular David Cowan did indeed marry a "Wright". Since we know from other sources that the first name of David (1)'s wife was "Jane" its easy to see why people think David (1)'s wife was indeed "Jane Wright". Unfortunately we do not indendantly know that the sister referred to here was indeed "Jane Wright" or even that James Wright had a sister Jane. It is entirely possible that the David Cowan of this record is not the David Cowan (1) who lived in Sevier County. In fact, the record itself suggests that he's not when it says that he made his deposition in "Jefferson County".
While there is a "Jefferson County, TN", and David (1) of Sevier County lived close to it, the record itself does not identify the state in which "Jefferson County" lay. From this we can infer that what was intended was that this David lived in Jefferson County, Virginia. Depending on the date, that could mean a reference to Jefferson County in what is now Kentucky, or to Jefferson County in what is now West Virginia. In 1808, when David gave his deposition, Kentucky had long since separated from Virginia, but what is now West Virginia was still part of the state of Virginia. Thus, this record probably refers to a David Cowan in what is now Jefferson County, West Virginia, and is not related to the David Cowan of Sevier County TN.
Note also, that this record gives David Cowan's age as 55 years in 1808, implying a DOB of 1753. This makes it quite quite impossible that this could be the same David Cowan who, with his wife Jane, sold his 268 acre tract in Albemarle County, VA in 1759, and is believed to be David Cowan (1). Moreover, David Cowan (1) is known to have had a daughter Eleanor born in 1761, which is again inconsistent with him being the David Cowan born in 1753, who married James Wrights sister.
The conclusion from this is that David Cowan originally of Albemarle County, VA moved to Castle's Woods in 1769 with his wife Jane, and after the Revolution, moved further south, settling in Sevier County TN, where he died after February 1811. It is very unlikely that his wife's last name was "Wright".