1 submit, for the consideration of Congress, scveral Communications received at the Department of State, from Mr. Justo Sierra, Com missioner of YucatÃ¡n, and also a communica tion from the Governor of that State, represen - ing the condition of extreme suffering to which their country has been reduced by an insurrec ion of the Indians vvithin its limits, and asking he aid of the United States. The communicationg present a case of human sufl'ering and misery which cannot fail to excite the sympathiesof all civilized nation. From t littse and other sources of Information, tappears that the Indians of YucatÃ¡n are wagng a war of extermination against the white race. In this cruel war, they spare neither age nor sex, but put lo death, indiscriminatey, all who fall within their power. The inlabitants, panic-stricUen and destitute of ai-ms, are flying before their savage pursuors towards the coast; and their expulsiÃ³n from their country, or their extermination, would seem lo be nevitable, unless they can obtain assistance 'rom abroad. In this condition they have, through their constituted authorities, implored the aid of this jovernment to save them from destruction, offering, in case this should be granted, to transfer the "dominion and sovereignty of the PenÃnsula" to the United States. Similar apicals for aid and protection have been made â o " the Spanish and the English Governments."' WhÃ¼st it is not ray purpose to recommend the adoption of any measure, wilh a view to the acquisition of the " dominion and sovereignty" over YucatÃ¡n, yet, according to our established policy, we could not consent to a transfer of this " dominion and sovereignty," either to Spain, Great Britain, or any other European Power. In the language of President Monroe, in his message of December, 1823, " we should consider any attempt on their part to extend their syslem to any portion of this hemisphere as dangerons to our peace and safety." In Ã¯ny annual message of December, 1845, I declared that " near a quarter of a century ago, the principie was distinctly announced to the world, in the annual message of one of my predecessors, that the Ameri can Continents, by the free and independent condition which they have assumed and maintained, are henceforth not to be considered as subjects For future colonization by any European Power." " This principie will apply wuh jreatly increased force, should any European Power attempt to establish any new colony in North America. In the existing circumstances of the world, the present is deemec? a propea occasion to reitÃ©rate and reaffirm the principie avowed by Mr. Monroe, and to state my cordial concurrence in its wisdom and sound policy. The reassertion of this principie, especially in reference to North America, is at ihis dav but the promulgation of a policy which no European Power should cherish the disposition to resist. Existing rights of every European nation should be respected ; but it is due alike to our safety and our interests, that the eflicient protection of our laws sliould be extended over our whole territorial lirnits, and that if should be distinctly announced to the world, as our settled pilicy, that no future European colony or dominio shall, with our consent, be planted or esiablished on any part of the American Continent," Ourown security 'equires that the eslablished policy, thus announoed, should guide our conduct; and Ãs applies with great force to the Penin8ulaof Yucalan. It is sitÃºate in the Gulf of Mexico, on the North American Continent; and, from its vicinity to Cuba, to the Capes of Florida, to New Orleans, and indeed our whole south western coast, it would be dangerous to our peace and secunty if it should becomo a colony of any European nation. We have now authentic information that, if the aid asked from the United States be not granted, such aid will probab'y be obtained from some European Power, which may hereafter assert a claim to " dominion and sovereignty" over YucatÃ¡n. Our existing relations with YucatÃ¡n are of a peculiar character, as will be perceied from the note of the Secretary of State to her Commissioner, dated on the 24th of December last, a copy of which is herewith iransmilted. YucatÃ¡n has never declared her independence, and we trat her as a State of the Mexican Republic. For this reason, we have never officially received her Commissioner ; buf. whilsl this is the case, we hope. to a considerable extent, recognised her as a neutral in our war with Mexico. Whilst still considering Yuca tan as a portion of Mexico, if we had troops to spare for that pui-pose, l would deern it proper, during the continuance of the war with Mexico, to occupy and hold military possess ion of lier territory, and to defend the white inhalitants against the incursions of the Inuians, in the same way that we have employed our troops in other States of the Mexican Republic, in our possession, in repelling the attacks of savages upon the inhabitants who have maintained their ncutraÃ¼ty in the war. - But, unfortunately, we cannot, at present, without serious danger, whhdraw our forces from other portions of the Mexican territory dow in our occupation, and scnd them to Yucatan. All ihat can be done, under existing circumstance8, 8 to employour naval forces in the Gulf, not required at olherpoints, toafford them relief. But it is not to be expectcd that any adequate protection can thus be afforded, as the operations of such naval force3 must, of necessity, be confined to the coast. I have considered it proper to communicate the informalion containeci in the acotnpanying conesporÃ¯dence, and 1 submit to the wisdom of Congress to adopt such mesures as, in iheir judgment, may be expedient to prevent YucatÃ¡n from becoming a colony of any European Power, which in no evem could be permitted by the United States ; and at the same time to rescue the white race from extermination or expulsiÃ³n from their country. James K. Polk. Washington April 29, 1848. This message nvolves great cardinal points, and a policy intimately connected with the prosperity of our nation, and should claim universal attention. Ã¯he Prosident in the present war with Mexico, claims indemnity for a faÃ¼ure on the part of the Mexicans to meet, what lie considera, thejust demands of our Government; and urges the prosecution of vigorout measures, not altogether to secure that indemnification ; but also to add California, and New Mexico, by conqnest, to the United States : making the acquisition of territory the ultÃmate object; as the overtures in the treaty eonclusively show, Wa cali the attontion of our reabre to an invftararion of' the policv, of llie commencemtiot, and jjroposod termination of the war ; to show that tha design of the Prenident is, to bring under tÃ¨a administration of our Government, all the country belween the United States, and tbc Pacific Ocean ; as the tono of this message with referonce to YucatÃ¡n, clearly demÃ³nstrales. Th tubject of giving relief to a auffering peopla should claim the delibÃ©rate and irnmediate attention of Congress. But with referenco to h3 allusion tu the intei-vention of ioreign powera, our country should pause, and take into consideration, the bearing, and tendency, of rneasures, that may involve it in undegirabl controversies. President Polk's design seems to be, not only lo extend our territorial limits as far as practicable, but to dÃctate to, and, should ha deern it necessary, to hold dominion over, tho whole of this Hemisphere. This is a high toned sentiment, and if uttered by the Execu tire of any other Government on this conlinent would be considered as an assumption not to be tolerated by us.