1)  that he was a French Huguenot immigrant to New England named Jean SIEYES;

2)  that he was born in New England, the son-in-law of William ROBERTS of Oyster River.

1.  Sybil Noyes, Charles Thornton Libby, & Walter Goodwin Davis.  1928-39.  Genealogical Dictionary of Maine and New Hampshire.  Southworth-Anthoensen Press, Portland, ME (republ. 1972ff by Genealogical Publ. Co., Baltimore, MD; Broderbund CD-523).  Regretably, the authors indicate that they "modernized" dates and spellings, so this is not a verbatim compilation of the record.  An example of the reason not to do such tampering is evidenced below by the inconsistency of John's record of military service in 1693-4.  Did the original say, "John Sias" or "John Cyas"?  We'll have to consult the original to be certain.  The authors' entire coverage of SIAS is given below, as found on p. 633 (bold-face as per original):

SIAS, very uncommon. 1 ____, mar. a dau. of William Roberts(14), who mar. 2d Salathiel Denbo(1) and 3d William Graves(6). Son John appears. See also (2). One John Size, residence unkn., was a soldier under Capt. Moseley in 1675. 2 HENRY (Sise), Oyster River 1690. List 57. See (1). 3 JOHN(1), Oyster River.  As John Cyas, credited to Ipswich, he was a soldier at Wells in 1693-4, m. there (Ct. 3 Jan. 1698-9) Ann Pitman(11), remov. to O.R. and in 1701 had a 20 a. gr. adj. his ho. She was bp. 7 June 1724, and depos. in Sept. 1755, ±89.  In 1747 he deeded homestead to s. Joseph who sold in 1756 to Samuel Demeritt.  Lists 267b, 386b (sic), 369. Ch: John, bp. adult 8 Oct. 1721, adm. to O.R. Ch. 1723, m. 16 July 1728 Hannah Sampson(5), who d. in Danville, Vt., in 1794.  In 1742 he and Salathiel Denbo, jr., were charged with counterfeiting in Newport, R.I.  4 or more ch. Hannah, b. 21 Aug. 1700, m. John Moore(18). Samuel, Lee 1765, ±64 in 1768. Will, 1774-1775, names w. Phebe, 6 liv. ch., gr.s. John Hill.  List 369. Judith, bp. adult 7 June 1724, m. Hercules Hunking(9). Rachel, m. Nathaniel Meader(4). Solomon, bp. adult 25 July 1725, of Lee 1765, w. Hannah. List 369. Clement, List 369; of Canterbury 1737. Capt. *Joseph, m. Ruth Matthews (Francis 6 jr.). 2 kn. daus. Often moderator and selectman at Durham; Rep. from Lee 1776-7; Justice of Inf. Ct. of Com. Pleas.

If Ann was ±89 when deposed in 1755, then she was born ca. 1666, not 1672.  There is no List 386b, and List 386 isn't applicable.  It must be a typo for 368b.  The asterisk indicates a Representative.

Pg	List No.	List
12	57	I can't figure why this entry was included because in it is a correction changing "Hen Sise to Rise" so it isn't remotely relevant to SIAS.
29	267b	Wells... 'A list of souldiers under the Command of John Hill.' [Nov. 8, 1693 - 23 Feb. 1693-4] men's names whare belong Capt. John Hill Wells Jos. Hill Sergt. --- Mark Pitman --- John Sias Epswich [This is a long list; I've only included individuals with surnames known (to me) to be related to SIAS.]
52	368b	Durham (Oyster River)... Five Petitions regarding a Separate Parish, 1715-1717. -- Stackpole's Durham, pp. 174, 176, 178, 180, 182. 178 After David Lyntard to Kyacard, 182 After Joseph Nudder to Medder.
	369	Durham (Oyster River)... Final Division of Common Lands, 18 March 1733-4 -- Stackpole's Durham 19-21.

2.  Walter Goodwin Davis.  1996.  Massachusetts and Maine Families in the Ancestry of Walter Goodwin Davis (1885-1996):  a Reprinting, in Alphabetical Order by Surname, of the Sixteen Multi-Ancestor Compendia (plus Thomas Haley of Winter Harbor and His Descendants) compiled by Maine's Foremost Genealogist, 1916-1963. Genealogical Publ. Co., Baltimore, MD (Broderbund CD-194).  In Vol. III, pp. 229-233, is a section entitled, "Roberts, of Oyster River, New Hampshire (from Lydia Harmon, 1924)."  This section appears to be a verbatim excerpt from The Ancestry of Lydia Harmon.  I cannot quote the section in its entirety because of copyright contraints, but here are the paragraphs most relevant to SIAS:

p. 229	...the Roberts farm was sold to William and Ezekiel Pitman on January 23, 1664...
p. 230	William Roberts and one of his sons-in-law were killed by Indians in 1675, during King Philip's War... From the account [of his estate] ... it appears that Roberts was survived by his wife and that his son, William Roberts, died before 1677...    The name of William Robert's wife is not known.     The number and names of William Robert's children are determined by the deeds disposing of the two hundred-acre town grants.  The property was conveyed in "one-fifth parts" by Elizabeth Allen, Sarah Harmon, Grace Moses and Hannah Cox, all stating that they were daughters of William Roberts.  This leaves only one fifth to be accounted for, and proves that at the date of the division no son of William Roberts was living to inherit a double portion.  The last fifth was held in shares, of which two were conveyed by John Sias and Ann, his wife, and one by Richard Denbow, on the same day, to Salathiel Denbow, who later conveyed all his rights in the property of his grandfather, William Roberts.  From these facts the theory is advanced that a daughter of William Roberts married, first, a Sias -- the son-in-law who was killed by the Indians with her father in 1675 -- by whom she had a son, John Sias, who inherited an eldest son's
p. 231	double portion of her estate and that she married, second, Salathiel Denbow, senior, and by him had several other children.    Children [of William ROBERTS]...   ii.  A DAUGHTER.  As stated above, there is evidence pointing to the conclusion that she m. _____ Sias, and, after his death in 1675, m. Salathiel Denbow.  Denbow was born in 1642, according to his own statement in a deposition.  He was in Oyster River in 1666, and d. before 1714.  The name was often spelled Denmore and is now Dinsmore.  His wife survied him and married William Graves as her last husband, he being named as their "father-in-law" by her children in their deeds of their Roberts inheritance.    Child, by first husband [Mr. SIAS]:--    1.  John Sias.  He m. Anne Pitman in Wells in 1698.  She was b. about 1672, and was undoubtedly the daughter Anne mentioned in the will of William Pitman of Oyster River in 1682.  They conveyed their two shares of land which formerly belonged to William Roberts to Salathiel Denbow in 1724.    Children, by second husband [Mr. DENBOW]:--...

The remainder of the section gives the children of Mr. & Mrs. (SIAS) DENBOW, then the remaining children of William ROBERTS.  Rather than quote further, I will incorporate this genealogical information in the family group sheets linked to this web page.  [UNDER CONSTRUCTION]

3.  Samuel C. Adams.  1878.  "Church Records of Rev. Hugh Adams, Principally at Oyster River Parish (now Durham), N.H." New England Historical and Genealogical Register 32(April): 133-136.

p. 133	BAPTISMS, &c...
p. 134	1723-4... June 7. Anne Sius and her Daur Judith Sius.
p. 135	1724-5... July 25. Solomon Sius, son of Anne Sius.

4.  LDS.  Family Search: Internet Genealogy Service: Ancestral File (AF) and International Genealogical Index (IGI).

5.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).

6.  Descendants of John Sias Sr. by Garey L. Marshall.

7.  Archives of the SIAS-L mailing list (online at RootsWeb.com).

8.  Mary P. Thompson.  1892.  Landmarks in Ancient Dover, New Hampshire.  Republican Press Assn., Concord, NH.  On pp. 17-18:

Beaver Brook, Beaver Pond, Beaver Pond Meadow    Beaver pond is mentioned March 6, 1729-30, when ten acres of swamp, granted to James Thomas in 1701, "up above Little river, at a place called Beaver Pound," were laid out to Ebenezer Smith.  And three score acres of upland and meadow, granted to Roger Rose, were laid out to John Smith May 13, 1726, beginninng at a white ash tree on the south side of "a meadow called the bever Pond medow;" thence running N.W. by N. 60 rods, to a maple; then S.W. by W. 22 rods, "where the two brooks meet in the medow," etc.     Beaver pond, formed by the over flow of the beaver dam below, is no longer to be seen, but the meadow where it stood is in the south-western part of Lee, between the site of Fox Garrison and North river.    This meadow seems to have been acquired last century by Ephraim Davis and John Sias.  It now belongs to Mr. Kenerson and Mr. B.F. Lang.  It was drained by Beaver brook, which was the outlet of the pond.  The beaver dam was on this brook, about ten rods from the old Sias house.  A spring, about 30 rods from the house is still called the Sias spring.    Two brooks are mentioned above.  One of them is now dry most of the year and has no name.  The other is Beaver brook, which flows from the meadow to the boundary line of Lee and Nottingham where it receives Davis's brook that rises back of Mr. Obadiah Davis's house.  It then runs half a mile northerly--contrary to the direction of the other brooks in this vicinity.