African urban populations are growing predominantly through types of settlement commonly referred to as ‘informal’– settlements constructed outside the control of city or state governments. For the UN New Urban Agenda, informal settlement presents a challenge to developing sustainable cities. Settlement qualification in urban development discourse often relies on prescriptive formal models and considers anything not complying to these as ‘informal’ and unsustainable. This paper advances informal settlement as an adaptive response to Western planning models that builds on regional histories of organising urban space. Examining archaeological and historical urban records from northern Ethiopia, we define spatial patterns and social processes of urban transition over millennia. In the analysis, settlements that in current urban debates fall under the ‘informal’ rubric contribute to building urban resilience. A century-scale resolution reveals contingent conditions for cities enduring climatic and socio-political shifts during the Pre-Aksumite and Aksumite periods (c. 800 BCE–CE 900) and afterwards. Past urban transitions were marked by inverse settlement dynamics: as urban cores shrank, peri-urban settlement grew and new centres were established. Although spatial reconfigurations followed political shifts, urban settlement remained largely consistent: urban landscapes of food production, material processing, resource trading and ritual making. In the Aksumite record, informal processes convey flexibility and diversity of settlement forms to undergo sustainability transitions. The durability of urban morphologies in the archaeological record warrants against stereotyping informal settlement as a challenge to sustainability transitions. A long-term perspective supports emerging approaches to informal settlement today as a locally adaptive property of urban systems.

中文翻译：

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（非正式）正式和解给谁？埃塞俄比亚可持续转型的考古学和旧城市议程


非洲城市人口的增长主要通过通常被称为“非正式”的定居点类型——在城市或州政府控制之外建造的定居点。对于联合国新城市议程来说，非正规住区对发展可持续城市提出了挑战。城市发展话语中的聚落资格通常依赖于规范性的正式模式，并认为任何不符合这些模式的事物都是“非正式的”和不可持续的。本文提出了非正规住区作为对建立在组织城市空间的区域历史基础上的西方规划模式的适应性反应。通过研究埃塞俄比亚北部的考古和历史城市记录，我们定义了数千年来城市转型的空间模式和社会过程。在分析中，当前城市辩论中属于“非正式”标题的住区有助于增强城市韧性。一项百年规模的决议揭示了前阿克苏姆时期和阿克苏姆时期（约公元前 800 年至公元 900 年）及之后城市经历气候和社会政治转变的偶然条件。过去的城市转型以逆向定居动态为标志：随着城市核心的缩小，城郊定居点的增长和新中心的建立。尽管空间重新配置伴随着政治转变，但城市聚落基本上保持一致：粮食生产、材料加工、资源交易和仪式制作的城市景观。在阿克苏姆记录中，非正式流程体现了定居点形式的灵活性和多样性，以实现可持续性转型。考古记录中城市形态的持久性证明，非正规住区的陈规定型观念是对可持续转型的挑战。 长远视角支持当今新兴的非正规住区方法，将其作为城市系统的本地适应性属性。