@Override
  public Call<List<DependencyLink>> getDependencies(long endTs, long lookback) {
    if (endTs <= 0) throw new IllegalArgumentException("endTs <= 0");
    if (lookback <= 0) throw new IllegalArgumentException("lookback <= 0");

    long beginMillis = Math.max(endTs - lookback, EARLIEST_MS);

    // We just return all dependencies in the days that fall within endTs and lookback as
    // dependency links themselves don't have timestamps.
    List<String> indices =
      indexNameFormatter.formatTypeAndRange(TYPE_DEPENDENCY, beginMillis, endTs);
    if (indices.isEmpty()) return Call.emptyList();

    return search.newCall(SearchRequest.create(indices), BodyConverters.DEPENDENCY_LINKS);
  }
To not produce unnecessarily long queries, we don't look back further than first ES support
zipkin-storage/elasticsearch/src/main/java/zipkin2/elasticsearch/ElasticsearchSpanStore.java