There was nationalism pre napoleon. Arguably east asia is a better example than european history IMO. I would say there is strong sense of nationalism among han chinese both now and in history. Likewise for Japan and Korea. Pre islam Persia as well. I guess the source of this was consistent centralized authority over a large region vs any technological change. You had that in east asia. You didn't have that in europe after roman times. Even larger empires like kingdom of spain were not really seen as "spain" as we know it but a unified monarchy over the kingdoms of castile, leon, aragon, sicily, and napoli. Interestingly you didn't really have that in india either, no one controlled the continent until mughal times and by then the religious and cultural regional differences were pretty set in stone.