Answer:
Without the specific excerpt to reference, it is difficult to determine the context of the statement. However, if the statement is accurately reflecting the excerpt, then the evidence that the Heian court was very wealthy is the fact that not only were the royal family members well dressed, but also the guards, grooms, and courtiers who were part of the procession. This level of fine dressing and attention to detail suggests that the Heian court had access to significant amounts of wealth and resources, which were used to support the court and its members in a luxurious lifestyle.