Although it was a well established theory that the capital was modeled after Changan of Tang Dynasty, its relationship with Fujiwara-kyo, previously thought to be close, became questionable, and therefore another theory became accepted, which stated that Rakuyo in Northern Wei Dynasty was the inspiration, yet the development of the capital was unique to Japan.
以前は唐の都の長安を模倣して作られたというのが一般的な定説であったが、先行する藤原京との密接な関係から現在は関連が疑われており、北魏洛陽などをモデルとした、日本独自の発展系ではないかという見方も有力となっている。