What do you meant by ttyl?

After reading this excerpt, darren makes a text-to-text connection. which example is a text-to-text connection?

The greatest gift the sumerians gave the world was the invention of writing. the sumerians were wealthy people. they needed some way to keep track of what they owned. they began drawing pictures. they used a reed as a pen. they drew on soft pieces of clay. the soft clay was then dried in the sun. the tablet became a permanent record. later, the sumerian drawings changed into wedge-shaped symbols. this kind of writing is called cuneiform. by putting symbols together, the sumerians could write entire sentences.

In 250 words, discuss the ways in which the novel relates to the historical context in which it was published.