The Short History of Git section of Chapter 1 states

For most of the lifetime of the Linux kernel maintenance (1991–2002), changes to the software were passed around as patches and archived files.

This was certainly true when the first edition of the book was released. It was possibly just barely true when the second edition was published. It has not been true for years. The sentence would be correct if it were reworded to say (for example)

During the early years of the Linux kernel maintenance (1991-2002), changes to the software ...