In a sea of doomsday ecological documentaries, Maureen Fazendeiro’s pastoral marvel is a sight for sore eyes. A solo debut feature for the Lisbon-based French director, this hybrid film studies the historical and geographical contours of Alentejo, a rural region in southern Portugal. The opening is set to a jaunty soundtrack of energetic percussion beats and twinkling organ notes, taking in the resplendent vistas of the landscape, with its rugged roads and lush vegetation. We see, too, a small archaeological tool hunt for ancient relics beneath layers of golden dust. Mirroring these acts of care and attention, Fazendeiro’s film takes the form of a cinematic excavation, fusing present-day tableaux with archival materials, folkloric legends with historical records.

The abundant use of tracking shots not only takes in the wondrous biodiversity of Alentejo but also facilitates a fluid movement between separate epochs. Observational scenes of green hills, boundless blue skies and roaming livestock are overlaid with narrated excerpts from second world war-era letters written by German archaeologists Georg and Vera Leisner. Credited with producing the first inventory of megalithic monuments in Alentejo, the pair imbues their wartime correspondence with the joy of discovery and the sadness of exile.

Elsewhere, history is preserved in oral tradition. One scene observes a circle of elders, in which a woman laments the rise of fascism and the fall of socialism in song, wistful melodies that reminds us of the years of António de Oliveira Salazar’s dictatorship. Another striking sequence takes a leap of imagination by re-staging a 17th-century myth. In weaving together these disparate threads of narrative, Fazendeiro’s sumptuous film offers an alternative form of geographical mapping, in which a landscape can be read like a text or a poem, to be preserved and passed on to future generations.

• The Seasons is at the ICA, London, from 25 September.