Whilst at the Newberry Library in Chicago, I read the following in Henry Hamilton’s journal of the Vincennes campaign, there is an interesting account of the links between the southern Indians, especially the Creeks, and the midwestern Indians, especially the Shawnees.

26th [ed. January, 1779]– The Chiefs of the following nations assembled at the fort this morning–Shawanese, Delawares, Wyandatts, Ottawas Chippoweys, Miamis, Ouiattanons, Quiquaboes, and Peankashaas–(239)
Egushewai rose up, and in the usual stile addressed the supreme being, thanking him for granting us this opportunity of assembling to speak our minds, expressed his good wishes to all present, to His Majesty, the great Chief at Quebec, all His Majesty’s Officers and Soldiers in the name of the chiefs present– then directed his speech to the Shawanese and Delawares, in particular, desiring them to be strong & to hold their Father by the hand as well as his Indian Children.
The master of life has no doubt taken compassion upon us since he has allowed us to assemble as friends in this place, let us then be sincere in our union, and act in concert for the defence of our lands. We see our father was foremost to rise up, and come thus far to frustrate the designs of the Virginians.
Brothers! You know there is a great tree under which we were used to confer peaceably and speak our minds, this tree grows at Detroit; let it be our study to keep that tree strait, that it may not bend to one side or another– The branches of this tree extend to a great distance and rise to the clouds, who is there capable of hurting even the bark of that tree? no one–
You may recollect that last spring some Chickasaas and Cherakees came to Detroit to water that Tree, I therefore recommend to you once more to be strong, & to defend your possessions, which your father is doing his best to preserve for us.
–The Shawanese Strangers then spoke– Father and you our brethren listen to us! five Moons are now passed since we left our Village to go to the Creek Country, from whence we are just arrived– When we last went from this place the Officer who commanded (Captn Helm) gave us a letter for the chief of the Creeks, but as we feared it might contain something contrary to the wellfare of the Indians, we have brought it back unopend, & now put it into your hands–
//This letter contained an exhortation to the Creeks, to discredit the reports of the English who always told them lies, to require them to remain quiet, assuring them that the Ouabache Indians had joined the Americans, and exulting the power and credit of the Americans.//
We have brought a Peoria Woman who was. a prisoner among the Creeks, and whom they deliverd to me, that I might bring her to her nation, but meeting Kissingua who told us he was allied to the Peoria nation, and who asked her of us saying he would deliver her to her friends, we gave her up to him–
There is a white man with him (Hazle)–
Kissingua desired us to tell his brethren of this river, to assemble any prisoners they may have among them belonging to the Creeks, as he designed bringing on his return any of their prisoners resident among the Creeks–
The Shawanese then produced a long white Belt from the great chief of the Creeks, which he desired might be forwarded to the Ouiattanons, and by them sent to the Lake Indians that all the nations might be acquainted with the friendly intentions of the Creeks towards them, and of their enmity to the Americans– that this belt opend a road of communication between them, which should always be kept dear, so as a child might walk with safety–
He then deliverd a twist of Tobacco for the same Indians, desiring they might smoke it, as the chief of the Creeks did, when he thought on good things, & had compassion on the Women and Children of his nation–
The Shawanese further said that the upper towns of the Creeks had not taken up the hatchet against the Americans until the last Spring, but that at present they were all engaged, and had made their way as far as to the Old Shawanese Villages, & had destroyed several small forts–
That the English had eight Forts on, and near the coast– that the Rebels had made an attempt on the greatest called the Stone fort, but that the Indians had met them on their March and repulsed them– That 800 of the inhabitants had come in to beg protection from His Majesty’s officers– That they were in the utmost distress for want of cloathing, and at variance among themselves– He added that the Southern Indians were never so well supplyed as at present, owing to the care of Mr. Stewart the Superintendant–

Substance of a Conference with the Indians, St. Vincennes, January 26, 1779, in I H C, I, 394-397. See also Hamilton to Haldimand, St. Vincennes, January 24, 1779, in ibid., 389-393.
I read in it in John D. Barnhart’s book Henry Hamilton and George Rogers Clark in the American Revolution with Unpublished Journal of Lieut. Gov. Henry Hamilton, edited by John D. Barnhart , (R. E. Banta, Crawfordsville, Indiana, 1951), but found it online here;
Source; http://www.in.gov/history/3010.htm Last accessed on 1 March 2011.

I think this is interesting to help make the case that the southern and midwestern Indians had more that just novel links. This seems to present the southern Indians, especially the Creeks, as fairly knowledgeable and supporting of the midwestern Indians attempts to keep the American settlers at bay. The Shawnees had familial links with the Muscogee [Creeks] people and they obviously used them to keep a communication channel open in the American Revolution.