During the Roman occupation of Gaul, the Latin language was imposed on the natives. This Latin language eventually developed into what is known as Vulgar Latin, which was still very similar to Latin. Over the centuries, due to Celtic and Germanic influences (particularly the Franks), la langue d'oïl was developed. A dialect of la langue d'oïl known as le francien was the language of the court, and thus became the official language of what was to become the Kingdom of France, and later the Nation-State of France. From medieval times until the 19th century, French was the dominant language of diplomacy, culture, administration, trade and royal courts across Europe. Due to these factors, French was the lingua franca of this time period.