Yemen

The Kingdom of Saba — Queen of Sheba's realm

The Kingdom of Saba (c. 900–115 BCE) — the south Arabian civilisation centred at Marib in modern Yemen, whose legendary queen visited Solomon in Jerusalem, whose engineers built the Great Dam of Marib (one of the ancient world's greatest engineering achievements), and whose merchants controlled the global trade in frankincense and myrrh — was one of antiquity's wealthiest civilisations, the source of the biblical "Queen of Sheba" tradition.

The Frankincense Road — Arabia's ancient trade corridor

Yemen's ancient frankincense and spice trade (c. 700 BCE – 300 CE) — which moved the aromatic resins of the Hadhramaut and Dhofar highlands by camel caravan through the Arabian Peninsula to Egypt, Rome, and the Mediterranean — made south Arabia one of the ancient world's wealthiest regions and generated the term "Arabia Felix" (Fortunate Arabia) among Greek and Roman geographers, in contrast to the "Empty Quarter's" barren interior.

The Zaydi Imamate — Yemen's thousand-year theocracy

The Zaydi Imamate (897–1962 CE) — the Shia Muslim polity established by Yahya ibn al-Husayn in the highlands of northern Yemen, persisting (with interruptions) for over a thousand years until the 1962 revolution — was one of the world's most enduring Islamic governing institutions and the foundation of the Houthi movement that drives Yemen's 21st-century civil war.

Aden — the British Empire's Red Sea gateway

Aden (1839–1967 CE) — the natural harbour at the southern tip of the Arabian Peninsula, seized by the British East India Company in 1839, developed into one of the world's busiest coaling and refuelling stations after the Suez Canal opened (1869), and relinquished after a bloody insurgency in 1967 — was the strategic hinge of Britain's Indian Ocean empire and the source of South Yemen's Marxist politics.

Yemeni unification — and its instant unravelling

The unification of North and South Yemen (22 May 1990 CE) — bringing together the conservative, tribal Yemen Arab Republic (Sanaa) and the Marxist People's Democratic Republic of Yemen (Aden) into the Republic of Yemen — lasted barely four years before a civil war (1994) in which the northern military crushed a southern secession attempt, generating the grievances that sustain the southern separatist movement (the Southern Transitional Council) to this day.

The Yemeni Civil War — the world's worst humanitarian crisis

The Yemeni Civil War (2014–present) — triggered by the Houthi movement's seizure of Sanaa, followed by a Saudi-led military coalition's intervention (2015), and producing a humanitarian catastrophe of 377,000 deaths (70% from indirect causes — disease, starvation, lack of healthcare) by 2021 — is the 21st century's most devastating conflict measured by civilian suffering per capita in the affected population.