"Individual carved slabs were placed together to create the great sloping talud of carved captives in the East Court of the Palenque Palace. Lords of the region would have entered the court by the staircase that these humbled figures flank."
Mary Ellen Miller, The Art of Mesoamerikca from Olmec to Aztec, p. 125
Regarding capture and sacrifice at Palenque and specifically about these particular figures, Claude Baudez & Peter Mathews write:
"One cannot help being struck with the feeling that something is wrong with this composition: there are four slabs on one side of the stairway, five on the other; the slabs are of the same height, but of variable width and general form. The figures are not facing the stairway, as one would perhaps expect in this situation, but rather all face south, except for the slab on the north end of each set...
None of these sculptures conforms to the Palenque art canons: the usual proportions of the human body are not respected: the heads are enormous and the attitudes clumsy. Furthermore, the sculptures not only differ as a whole from the Palenque works; they also differ from one another.
From the uneven number of the slabs on each side of the stairway, from their orientation, their variation in size and proportions, their differences in style, the slight modifications (cut offs, filled blanks) brought to their original form, it may be concluded that the slabs come from outside Palenque, from different sites, and possibly at different times.
...We have suggested above that the slabs were made by different artists, and not Palencanos. One may wonder why Palenque, which used the services of extremely skilled artists, ordered sculptures from abroad. We would suggest that the several captive figures were each made by a conquered people, who had to pay as tribute to the victor an image of their humiliated ruler."
Claude F. Baudez & Peter Mathews, Capture and Sacrifice at Palenque, p. 5 –7.
Prisoner slabs on right side of stairway
"This courtyard contains representations of noble prisoners taken by the kings of Palenque.
The hieroglyphics on the loin cloths of these prisoners records details of their identity and capture. Ritual warfare and the capture of neighboring kings or nobles for sacrifice was part of the obligation of kingship.
"In a similar way, the drawing from Tonina Monument 122 shows a reclining figure identified by three glyphs incised on his right thigh.
These read, "Kan Xul II of Palenque," who was the son of Pacal the Great and younger brother of Chan-Bahlum. The date carved along the right hand edge of the stone records the date of his capture by Tonina Ruler 3 in A.D. 711.
Linda Schele has proposed that the carving style of Monument 122, in the tradition of Palenque rather than that of Tonina, may be evidence of the tribute paid to the victorious polity by Palenque — a master stone sculptor dispatched to Tonina to carve the monument commemorating the defeat of his former king.
A more recent discovery at Tonina settles the issue of Kan Xul's fate — a sculptural panel depicts the Palenque ruler's severed head."
Robert J. Sharer, The Ancient Maya, p. 295.
Drawing by Linda Schele, ©David Schele, courtesy Foundation for the Advancement of Mesoamerican Studies, Inc., http://www.famsi.org