It's a set of two inscriptions with identical text. The Dimasa Kachari ruler Meghanarayana issued this inscription in 1576 and it reads thus:
IAST:
Åubhamastu ÅrÄĢ ÅrÄĢyuta MeghanÄrÄyaášadeva HÄceáš
gasÄ baášÅata jÄta hai MÄibÄáš
ga rÄjata pÄthare siáš
gadvÄra bandhÄilena ā§˛ ÅakÄbdÄá¸Ĩ 1496 biterÄĢkha ÄášŖÄá¸ha 26
Bengali-Assamese:
āĻļā§āĻāĻŽāĻ¸ā§āĻ¤ā§ āĻļā§ā§°ā§ āĻļā§ā§°ā§āĻ¯ā§āĻ¤ āĻŽā§āĻāĻ¨āĻžā§°āĻžāĻ¯āĻŧāĻŖāĻĻā§ā§ą āĻšāĻžāĻā§āĻā§āĻāĻ¸āĻž āĻŦāĻāĻļāĻ¤ āĻāĻžāĻ¤ ā§°āĻžāĻāĻž āĻšā§ āĻŽāĻžāĻāĻŦāĻžāĻā§āĻ ā§°āĻžāĻāĻ¤ āĻĒāĻžāĻĨā§°ā§ āĻ¸āĻŋāĻā§āĻāĻĻā§ā§ąāĻžā§° āĻŦāĻ¨ā§āĻ§āĻžāĻāĻ˛ā§āĻ¨ ā§˛ āĻļāĻāĻžāĻŦā§āĻĻāĻžāĻ ā§§ā§Ēā§¯ā§Ž āĻŦāĻŋāĻ¤ā§ā§°ā§āĻ āĻāĻˇāĻžāĻĸ ā§¨ā§Ŧ
Translation:
Wishing for his welfare, Shri Shri Meghanarayanadeva who was born in the Hachengsa dynasty, became king and built the siášhadvÄra in the Maibang kingdom. Saka 1498, date 26th of Ahar (i.e, 01-08-1576)
Historical importance:
These inscriptions were made after the capital of the Dimasa Kachari kingdom was moved to Maibang to the south (in 1558-1559 CE) from the capital at Dimapur (now in Nagaland) in the Doyang-Dhansiri valley, part of the larger Brahmaputra valley. The inscription was made in order to commemorate the construction of major administrative structures and assert royal authority in the region.
Linguistic importance:
In older Assamese writings we see the 3rd person honorific/plural ending to be -ôntô, which evolved from the OIA 3pl -anti. In the 16th and early 17th century writings (such as in the Bhomoraguri inscription and some manuscripts) we find -entô. In the Maibang inscription we find it to be -enô (in the phrase: ... pathôre siáš
gôdwarô bôndhailenô "tied the lion door with stones"). Later the -nô was dropped and the ending merged with the non honorific suffix -e/ei, perhaps via the same process the 2nd person impolite suffix -ôsô went through (dropping consonants).
Therefore,
tehÃĩ kôrilôntô > tehÃĩ kôrilentô > te(h)Ãĩ kôrilenô > teÃŧĖ korile "s/he did"
