Japanese construction techniques and architectural styles changed in the eighth century C.E. from more traditional Japanese models to imported continental (especially Chinese) models. Several factors contributed to this, in particular with respect to the creation of two new capital cities. In essence, changes then occurring in Japanese political life were rendering past arrangements for the rulers’ headquarters obsolete, and continental models offered an alternative.

To elaborate, before the eighth century, the elite marriage practice, which was an important instrument of political alliance making, had encouraged rulers to maintain multiple palaces: that of their own family and those of their spouses, who commonly remained at or near their native family headquarters, at least for some years after marriage. These arrangements had the effect of encouraging frequent changes in royal residence as children matured and marriage alliances changed. The customs of multiple palaces and a moveable court were feasible as long as a ruling group was modest in size and its architectural practices relatively simple.

Moreover, because buildings using the traditional construction of thatched roofs and wooden poles placed directly in the ground rotted away in two decades or so, periodic replacement of palaces, shrines, warehouses, gate towers, and fortress walls was essential. The custom of residential mobility was thus not especially wasteful of labor and material resources: when the time came, one simply erected a new building at a new site—reusing valuable timbers as appropriate—and burned the rest. The practical necessity of replacement was given religious sanction because the regular replacement of buildings was regarded as necessary to provide spiritual cleansing of the site.

As rulers of the sixth and seventh centuries expanded their realm, however, they acquired more and more underlings, administrative paraphernalia, weaponry, and tribute goods, and they needed more and more buildings to house them. As the scale of government grew, moreover, it became more important to have these people and resources close at hand where they could be more easily controlled and utilized. Under these circumstances, frequent moves by the court or replacement of buildings became more costly, even prohibitive.

A solution to the problem was advocated by experts from the continent. This was the use of continental principles of urban design and techniques of construction. These produced geometrically laid out capital cities whose major gates and buildings employed stone foundations, mortise-and-tenon framing (a technique for attaching timbers), and tile roofs that largely eliminated the problem of rot and the consequent need for replacement.

On the other hand, to construct cities and buildings of that sort required so much labor and material that their use effectively precluded periodic replacement or the transfer of a royal headquarters from site to site. Nevertheless, the notion of grand buildings and capital cities became immensely attractive to Japanese rulers during the seventh and eighth centuries. Continental regimes, the glorious new Chinese dynasties most notably, had them: they constituted an expression of political triumph, a legitimizing symbol of the first order. Moreover, the architecture was an integral part of Buddhism, and acceptance of this religion in Japan at this time fostered adoption of its building style.

These several conflicting factors—the need to modify palace and capital arrangements but the difficulty of doing so, the wish to enjoy grandeur but the reluctance to settle for a single, immobile court—all became evident by the mid-seventh century. Change did come, but slowly, and in the end a compromise system was devised. Traditional shrines of Shinto, the native religion of Japan, and many residential buildings continued to be built in the rottable, replaceable style that accommodated religious concerns and taboos, while city gates, major government buildings, and Buddhist temples were built in the continental fashion that met the need for permanence and grandeur. Moreover, the wish of rulers to maintain multiple palaces fit with the custom of certain continental regimes that maintained summer palaces or other regional capitals where rulers could periodically reside on a temporary basis.

日本的建筑技术和建筑风格在公元的第八世纪发生了变化，从更传统的日本模型变为了进口大陆 (特别是中国) 模型。有几个因素促成了这一点, 特别是在建立两个新的首都城市方面。实质上, 在日本政治生活中发生的变化使统治者总部的过去安排过时, 大陆模式成为了替代方案。 详细的来说，在第八世纪之前，作为政治联盟重要工具的精英婚姻鼓励着统治阶级拥有多个宫殿：至少在婚后的几年内，有他们的家人的宫殿和他们配偶的宫殿，通常是在家庭主要住宅的附近。这些安排的效果是随着其孩子的长大和婚姻联盟的改变，鼓励皇室住宅的多变性。只要一个统治集团规模不大，建筑工程相对简单，多处宫殿和一处可移动的宫廷的风俗是可行的。 此外，因为建筑使用的是传统结构，如茅草屋顶和木头柱子直接搭建在地面上，使其在两年左右的时间就腐烂了，所以，定期更换宫殿、神社、仓库、城门塔和堡垒墙是必不可少的。因此，住宅流动化的习俗并没有特别浪费劳动和物力资源。当时间到了，你只需要在一个新的地点建起一座新的建筑，适当的重新利用有用的木材，烧毁其他的木材即可。由于有必要对建筑物进行定期更换，以提供对宫殿的精神清洗，因此，人们便对替代的实际必要性给予了宗教仪式。 然而, 作为扩大了领土的第六和第七世纪的统治者,他们获得了越来越多的下属、行政工具、武器和进贡物品,他们就需要越来越多的建筑物来容纳这些。此外，随着政府规模的扩大, 把这些人和资源握在手中以便控制和利用的观念变得越来越重要。在这种情况下，宫廷经常采取行动或更换建筑物的行为花费更加昂贵,甚至令人望而却步。 大陆的专家们认同解决这个问题的一种方法，就是使用大陆原则的城市设计和技术的建筑。这些产生几何布局的首都城市,其主要的大门和建筑物使用的石头基础、榫和榫框架(附加木材的技术)和瓷砖屋顶,极大地解决了腐烂问题和需时常更换的麻烦。 另一方面, 建造这种类型的建筑物需要大量的劳动力和材料, 他们有效地使用排除了定期更换或将皇家总部从一个地方转移到另一个地方的麻烦。然而,在第七和第八世纪,大建筑和首都城市的概念对日本统治者有极大的吸引力。大陆政权就拥有这样的建筑，尤其在光辉的新中国朝代，因为这些建筑彰显了政治胜利, 是第一个命令的合法化标志。此外, 该建筑是佛教不可分割的一部分, 在日本接受这一宗教的时期提倡了采用其建筑风格。 这几个相互矛盾的因素——很难同时做到的修改宫殿的需要和资本安排、不愿为一个单一不稳定的宫廷定居下来却想享受宏伟建筑的愿望，所有这些都在第七世纪中叶变得显著。变化确实出现了,但是缓慢的,最终人们想出了一个妥协机制。传统的日本神道教圣地,即日本的本土宗教，和许多住宅建筑继续在建造中，却也是易腐烂的、可替换的包含着宗教的关系和禁忌的风格,而城市里的大门,主要是政府建筑的大门,和佛教寺庙是以大陆的方式建造的,满足了持久性和宏伟的需要。此外,统治者希望保存符合某些大陆政权风俗的多座宫殿, 在这些制度维持着的夏季宫殿或其他地方首都建筑里, 统治者可以在临时的基础上定期居住。