Hematopoietic stem cell (HSC) emergence in the human embryo is spatially and temporally regulated by highly concerted signals received from the microenvironment. Whilst this signaling has been increasingly well-characterized in model organisms, a deeper understanding of the specific human niche is required. HSC emerge in the ventral portion of the dorsal aorta from around Carnegie stage (CS)14 (33 days post fertilization) until CS17 (41 days post fertilization). We have previously characterized signaling within the HSC developmental niche towards the end of this temporal window, at CS16 and CS17, identifying a ventrally polarized signaling factor, Endothelin-1, as a pro-hematopoietic factor. In this present study we have instead focused on the beginning of this temporal window to identify the signaling events at the very onset of HSC generation and, in doing so, have generated an extensive and interactive resource for use in refinement of HSC derivation cultures ex vivo. We use spatial transcriptomics to explore dorsal-ventral polarized signaling in the dorsal aorta at CS13, just prior to the onset of HSC generation, and at CS14, when HSC generation is first initiated. We discovered that inflammatory signaling was consistently ventrally enriched at both stages with further enrichment at CS14 compared with CS13 including TNF alpha regulated pathways. Using single cell RNA-seq analysis of hematopoietic stem/progenitor, aortic endothelium and sub-aortic stromal cells, we were able to resolve these signaling pathways to discrete populations. Pathways, such as TNF alpha, span multiple cell types allowing intercellular networks of communication to be delineated. Furthermore, we generated an interactive web tool that facilitates user exploration of ligand-receptor interactions between spatial domains and cell populations of the spatial and single cell datasets respectively. Hematopoietic stem cell (HSC) emergence in the human embryo is spatially and temporally regulated by highly concerted signals received from the microenvironment. Whilst this signaling has been increasingly well-characterized in model organisms, a deeper understanding of the specific human niche is required. HSC emerge in the ventral portion of the dorsal aorta from around Carnegie stage (CS)14 (33 days post fertilization) until CS17 (41 days post fertilization). We have previously characterized signaling within the HSC developmental niche towards the end of this temporal window, at CS16 and CS17, identifying a ventrally polarized signaling factor, Endothelin-1, as a pro-hematopoietic factor. In this present study we have instead focused on the beginning of this temporal window to identify the signaling events at the very onset of HSC generation and, in doing so, have generated an extensive and interactive resource for use in refinement of HSC derivation cultures ex vivo. We use spatial transcriptomics to explore dorsal-ventral polarized signaling in the dorsal aorta at CS13, just prior to the onset of HSC generation, and at CS14, when HSC generation is first initiated. We discovered that inflammatory signaling was consistently ventrally enriched at both stages with further enrichment at CS14 compared with CS13 including TNF alpha regulated pathways. Using single cell RNA-seq analysis of hematopoietic stem/progenitor, aortic endothelium and sub-aortic stromal cells, we were able to resolve these signaling pathways to discrete populations. Pathways, such as TNF alpha, span multiple cell types allowing intercellular networks of communication to be delineated. Furthermore, we generated an interactive web tool that facilitates user exploration of ligand-receptor interactions between spatial domains and cell populations of the spatial and single cell datasets respectively.