Lotharingia emerged in the mid-ninth century as the longitudinal middle kingdom of the Carolingian Empire, carved out by dynastic partitions and dissolved within a generation. Yet the region endured as both memory and practice—a liminal borderland, never fully assimilated into either French or German polities but continually marked by overlapping sovereignties, plural legal traditions, and shifting linguistic frontiers. From the early Middle Ages onward, Lotharingia exemplified what Mary Louise Pratt terms a contact zone: a hybrid arena where imperial strategies, local practices, and vernacular cultures converged. Its aristocracies sustained autonomy by cultivating neutrality, striking diplomatic balances, and forging strategic marital alliances, embodying the negotiated and adaptive character of frontier politics. The legacy of Lotharingia persisted most visibly in Lorraine/Lothringen, where successive contests between France and Germany reinscribed its borderland condition. Transformed from Carolingian Kingdom to medieval duchy, and later into a repeatedly annexed and militarized frontier, the region epitomized Europe’s enduring “in-between” condition—fragmented, hybrid, and perpetually reshaped by conquest, cession, and resistance. In this sense, Lotharingia illustrates the sedimented quality of borderlands, where recurrent acts of division and integration deposited successive layers of meaning onto prior identities, so that its liminality endured as a central feature of Europe’s geopolitics and cultural memory.