Why were early Romance texts first written in northern France?

The emergence of early Romance languages texts in northern France is primarily attributed to the fact that, in that region, the Vulgar Latin spoken by the population had undergone more radical changes than in other areas.1

Following the collapse of the Roman Empire and the subsequent barbarian invasions, northern Gaul experienced significant linguistic shifts due to the influence of Germanic tribes, such as the Franks, and increased isolation from Rome. Because the spoken language in the north diverged more sharply from traditional Latin than the more stable, cultured dialects of the south, the need to document the vernacular in written form became apparent earlier in the north.21

The Strasbourg Oaths (842 CE) serve as the earliest example of this transition, representing a deliberate attempt to record the vernacular when the Latin alphabet was not fully equipped to capture the evolving speech.213