Results on Λ, Λ̅ , and Ξ- production in centrality selected Pb+Pb reactions at 40A and 158A GeV and in near-central C+C and Si+Si reactions at 158A GeV are presented. Transverse mass spectra, rapidity spectra, and multiplicities in dependence of the system size are discussed. Comparisons to transport models (ultrarelativistic quantum molecular dynamics and hadron string dynamics) and to the core-corona approach are performed. Although Λ and Λ̅ production can be described by transport models reasonably well, these models do not agree with the Ξ- measurements. However, the core-corona picture fits very well the system-size dependence of Λ and Ξ-, whereas it agrees less well with the Λ̅ data.