Background: Hematoendothelial progenitors (HEPs) generate cells of the hematopoietic and vascular systems. The major anatomical sites of hematopoiesis change during an organism's lifetime and new blood vessels can form in response to injury and disease. In a developing embryo, the first hematopoietic stem cells (HSCs) are of mesodermal origin, and arise from the lateral plate mesoderm, undergoing an endothelial-to-hematopoietic transition, to become HSCs. However, the gene regulatory networks (GRNs) involved in HEP specification, along with their epigenetic regulation, are currently unresolved. Cis-regulatory elements (CREs), such as enhancers, promote transcription of genes required for complex developmental processes and are therefore important when considering cell specification. Using the chick embryo as our model organism, we performed 10X multiome (scRNA-seq and scATAC-seq) library preparation followed by Illumina sequencing across two crucial developmental stages, on tissue where a previously identified enhancer for TAL1, a master blood regulator, was active. Subsequent analysis of this dataset was performed using Seurat and Signac. Utilising well-established cell type specific markers, as well as looking at the top differentially expressed genes in each cluster, we identified 14 different tissue types in our dataset including blood, endothelial, hematopoietic stem cells, and lateral plate mesoderm. Novel targets for tissue-specific CREs were identified, by looking at regions close to genes which regulate HSC formation including TAL1, GATA2, RUNX1, and LMO2. Using a fluorescent reporter plasmid to validate these targets, along with high-resolution fluorescent microscopy, the activity of each CRE was monitored during embryonic development.