Dresden Codex

This is an image from one of the remaining Mayan Codices [this particular piece forms part of the Dresden Codex]. The Mayans used ideograms [although this is a debatable description as the term grapheme or morpheme may be more accurate]to document their history/religion/science/prophecies/agricultural cycles/culture etc. The scribes who produced these works were said to be communing with the Gods often using an imagined spiritual realm as the frame of reference.
The codices date from around 1900 B.C. [the same time as the Egyptian papyrus scrolls]. Interestingly they were folded documents as opposed to long scrolls, suggesting that the intention was to read them in sequence, as pages rather than as a long panoramic image.

So the ideograms or morphemes or graphemes are the square-ish looking forms, ranged like blocks of type. They are image/text that convey particular information. What is interesting is the additional use of image or Illustration to support the information contained in the image/text, if that is what it does. If its purpose is decorative then it would serve to illuminate not illustrate.